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This article is a travel topic.
Scuba diving is an activity in which you swim underwater for extended periods using Self-Contained Underwater Breathing Apparatus, hence the acronym SCUBA, or Scuba.
Scuba diving is an excellent way to see some very beautiful sites: Tropical coral diving sites with their colourful sea life are the most famous but other scuba diving attractions include tropical and temperate rocky reefs, shipwrecks, caverns and caves.
Scuba diving can also be a very relaxing sport and in many places it's very beginner friendly. Many dive sites are accessible (under the care of an instructor) after a short briefing and training dive. You can learn to dive far more quickly than you can learn snow sports, for example, and a high level of fitness and strength is not always necessary. It's also suitable for people with a number of physical disabilities. As long as you can use the breathing equipment and are able to successfully propel yourself underwater you may be able to dive (see also Stay healthy).
Related topics include snorkeling, which generally refers to swimming on the surface while breathing through a snorkel, free diving, which involves breath hold underwater swimming, and SNUBA, which provides a surface source of pressurised breathing air, supplied to the diver through a limited length of hose and a mouthpiece.
Diving is a major travel activity: dedicated divers plan entire dive holidays, and others may want to include dive sites in their itineraries. Major dive destinations include:
Africa has a long coastline, and the coastal waters range from the warm tropical Red Sea, to the cool temperate west coast of southern Africa. The east coast of Africa is better known for diving destinations than the west coast or the Mediterranean coast, and there are good diving destinations scattered along the east coast from Egypt to South Africa, wherever accessibility and political stability allow.
The infrastructure varies enormously and is constantly changing. Availability of Nitrox, for example, is known from Egypt and South Africa. In some other places the availability of medical oxygen may be in question. Emergency medical facilities are also variable. Don't assume that anything is available at any specific destination. Ask and get written confirmation or book through certified operators and agents.
Djibouti has a unique ecosystem where the mix of the Red Sea and the Indian Ocean results in an abundance of marine life. Between the months of September and January Djibouti is home to resting migrating whale sharks. It is common to see many whale sharks, including juveniles, which tend to stay close to the coast during their visit.
Seven Brothers Islands is a major attraction to Djibouti waters. This breathtaking reef system is north of the Devils Cauldron, and comprises seven islands covering a vast area. Monumental drop-offs with stunning soft corals carpeting the walls, schooling fish and big pelagics can all be expected.
The Egyptian coast along the Red Sea in both Africa and the Sinai peninsula is a favoured destination for Scuba diving and snorkeling. Various dive centers operate in each resort town or city to arrange both recreational and educational trips for all levels of experience and budgets. Nuweiba is located in the South Sinai area. It is a relaxed small town with a large choice of shore diving and is ideal for the photographer. There are a number of dive centres which do guided dives for the experienced and courses for the novice through to tec diving. There are several hotels, small accommadations and beach camps to choose from. If you want a place to 'get away from it all' and destress this is it. It can be reached by flying into Sharm el Sheikh or Taba and then a transfer.
Malawi is a landlocked country, but it has a long coastline on Lake Malawi, with good freshwater diving.
Mauritius is completely encircled by a coral barrier reef and is home to many sponges, sea anemones and a variety of multi-colored tropical reef fish such as the Damselfish, Trumpetfish, Boxfish, Clownfish and the Mauritian scorpionfish with its unique orange color.
Most of the Dive sites are located on the west coast around Flic-en-Flac, in the north, at Trou aux Biches or at the Northern Islands.
Besides the coral reefs, there are ship wrecks dating back to the 18th and 19th centuries, and ships sunk more recently which create beautiful artificial reefs.
The best time to go diving is from November to April when the visibility is very good.
Some of the popular dive sites of Mauritius are:
- Cathedral which is located off the Flic en Flac on the western coast of Mauritius.
- Whale Rock
- Roche Zozo, an underwater rock pinnacle.
- Ile Ronde has a nearby submerged volcanic crater.
Mozambique is located on the southeast coast of Africa.
Mozambique has a tropical climate with two seasons, a wet season from October to March and a dry season from April to September. Rainfall is heavy along the coast and decreases in the north and south. Cyclones are common during the wet season.
Mozambique has nice coral, with colouful reef fish and invertebrates, but is known more for its abundance of manta rays, reef sharks, whale sharks and humpback whales.
South Africa has sites spread along its coast that are well known for sharks and other large marine animals, but also have a large range of endemic smaller fish and invertebrates. The coastal sites range from tropical coral reefs in the north of KwaZulu-Natal, where the fish are typical Indo-Pacific tropical species, and very colourful, to cool temperate rocky reefs on the West Coast, where the fish life is relatively dull, and the largely endemic invertebrates provide the colour.
The annual sardine run up the east coast is justly famous, with huge baitballs and a large variety and number of predators, from Bryde's whales down through dolphins, sharks, gamefish and seabirds.
There are a large number of wrecks along the coast, some of which are regarded as good dive sites.
The inland sites are more usually used for training, technical and cave diving.
Major diving destinations include:
- Cape Town — Diving the Cape Peninsula and False Bay
- Durban — Diving in Durban
- Port Elizabeth — Diving in Port Elizabeth
- Umkomaas — Diving Aliwal Shoal
- Sodwana Bay — Diving Sodwana Bay
- Mossel Bay
- Plettenberg Bay
- Port Alfred
Other diving destinations include:
- East London
- Jeffrey's Bay and St Francis Bay
- Margate (Protea Banks)
- Inland dive sites including: Bass lake, Badgat, Boesmansgat, Miracle Waters and Wondergat
Includes the islands Zanzibar and Pemba.
Zimbabwe is located north of South Africa. Political and economic instability mean that Zimbabwe is not currently recommended as a tourist destination.
There are only two known diving spots:
Scuba diving destinations in Asia are mostly concentrated in the Middle East and South East Asia, where the water is warm and visibility is usually good. These regions mostly have a tropical coral reef ecology, and there are a number of notable wreck diving sites.
- The Red Sea, particularly the Sinai Peninsula (Egypt) commonly known to host some of the most captivating dive sites in the world from wrecks to reefs.
- Dahab — home to the notorious "blue hole"
- Sharm el-Sheikh
The untapped potential here is huge, but for now diving is centered around Havelock Island, and while it's great you leave satisfied yet hungering for what you didn't see but know must be out there. As tourism on the islands increases large numbers of new dive sites should become known.
Located in the Bay of Bengal the Andaman & Nicobar Islands are a few of the destinations that have so far escaped the clutches of mass tourism. The peak diving season in Andaman Islands is between October and May. The aqua blue waters give good visibility and the area is abundant in marine life.
The Havelock and Neil Islands are the most visited due to their beaches, laid back vibe and Scuba facilities. The place has still not been overwhelmed by tourism, though Scuba diving is fast becoming a popular activity. These islands can be reached by a ferry departing from Phoenix Bat Jetty in Port.(?)
Dive sites at Lakshadweep are clustered around Agati, Kadmat and Bangaram islands.
Goa is India's top dive destination, but mostly just because it's the easiest to get to — visibility is usually only 5-6m. Diving season is mid-October to mid-May.
Menjangan Island in the north-west, and Tulamben (USS Liberty wreck) and Amed in the east, offer pleasant and accessible shore diving through wrecks, walls and reefs. Divers visiting Bali often base themselves at Lovina, Candidasa and Amed to access the sites.
Gili Islands and Lombok
Intermediate to advanced diving, with occasionally strong currents.
Wall diving at Bunaken.
Izu Peninsula in Shizuoka prefecture is a popular destination for mainland Japan diving. The East Coast of Atami is most popular with dive operators for its accessibility and infrastructure, while the West Coast's sites are largely unspoiled, safeguarded from weekend crowds by its remoteness and lack of train stations.
The southern islands of Okinawa have great diving, but prices are steep: you can expect to pay upwards of $100 for two dives.
Manta rays, hammerheads and mysterious underwater ruins.
- Aqaba On the Gulf of Aqaba off the Red Sea
- Perhentian Islands — home of sea turtles and many species of sharks on the east coast of Peninsular Malaysia. Great diving deals because of fierce competition.
- Pulau Tioman — Splendid coral, fish, turtles and reef sharks off the Malaysian East Coast
- Sipadan in Malaysian Borneo — Large biodiversity with 3000 species of fish and reef diving on a wall that descends 600m into the ocean
- Mabul in Sabah, East Malaysia. Muck diving ecosystem.
- Pulau Dayang For a less touristy but equally good dive spot, which can be reached by dive boat from Mersing
Crystal clear water with over a thousand coral islets to explore.
Deep in the middle of the Indian Ocean, the entire country is built on coral reefs and has some of the best diving on the planet. Prices for accommodation and diving services are expensive, though, and currents can be strong on the outer reefs.
- Fahl Island
- Salalah — has sea kelp and coral – an unusual combination of cold and warm sea organisms.
With 7107 islands, 18,000 kilometres of shoreline and 27,000 sq. kilometres of coral reefs, the Philippines lies in the coral triangle which is one of the most bio-diverse marine regions on Earth. The Philippine seas are home to over 450 species of hard corals,and more than 500 fish families, which include 2000-2500 fish species.
There is a wide variety of dive site types, including reefs, wrecks and underwater caves. The geographic location predisposes the Philippines to typhoons for four months in a year, but the topography and structure of the archipelago give make many of the site accessible througout the year.
English is spoken in most parts of the country
Dive sites include:
- Anilao — Outstanding corals and reef life with high diversity of small marine creatures.
- Mainit Point
- Beatriz Rock
- Apo Island — Protected diving area for over 20 years. Healthy corals.
- Apo reef — A 340 meter-wide dual-lagoon system divided by a narrow channel that runs west to east. This is an area where more than 380 species of fish are known to reside, an excellent area to view several species of large pelagics.
- Balicasag Island
- Cabilao Island — suitable for the more experienced diver. This dive site is noted for sightings of Hammerhead Sharks in the deeper waters off the island's northwest point.
- Boracay — A popular place in the Philippines to become certified. Quality beginner diving as well as a few good intermediate dive sites.
- Moalboal, Cebu
- Pescador Island (Moalboal)
- Sunken Island (Moalboal)
- Malapascua, Cebu
- Dona Marilyn Wreck (Malapascua)
- Gato Island (Malapascua)
- Coron, Palawan
- Tae Maru (Concepcion Wreck) — The Tae Maru is a 168 meter-long oil tanker that was sunk during a 1944 air raid that has a smashed bow and lies at 26m, listing slightly to port.
- El Nido, Palawan — a marine reserve, a dugong stronghold in the Philippines, and an excellent destination for snorkelers and beginner divers with impressive coral reefs and walls.
- Miniloc Island
- Puerto Galera
- Hole in the Wall
- Oryoky Maru (The Hell Ship) — This wreck site is now a tangled mass forming an artificial reef with good marine life. This wreck is notorious for its bloody history. Sunk in a US air attack during World War II, it was subsequently discovered that more than 1,600 American prisoners of war were onboard, all of whom perished in the attack.
- Tubbataha reef (Palawan) — a UNESCO World Heritage Site
- Tubbataha North
- Verde Island Passage — The Verde Island Passage was identified by noted American Marine Biologist, Dr. Kent Carpenter, as the center of the center of marine biodiversity. This area is reputed to have the most number of species per square meter of coral reef.
- Verde Island Wall
Notoriously difficult to visit, but hence very well-preserved, and now open to tourists who can book well in advance
- Ko Tao in south eastern Thailand: great for beginners and one of Asia's most popular places to get certified.
- The Similan Islands in south western Thailand — Widely regarded as some of Thailand's best diving. 70 km due west of Phang Nga, best accessed via liveaboard or a lengthy boat ride from Khao Lak. The Krabi region (Ko Lanta, Ko Phi Phi etc) nearby is similar and rather more accessible.
See One month of Southeast Asian diving and culture for a possible trip.
The country has a tropical climate with two seasons, a wet season from October to March and a dry season from April to September. Diving is best between March and December.
With a 3000m deep Wetar Strait just off the north coast, a fantastic array of coral and sea life can be found, most of it straight off the shore. This is a world class dive spot that few know about. It is also a whale hot spot.
Hon Mun Island - Marine Park Nha Trang
The majority of the dive sites are within a 1 hour boat ride (or 15 minutes by speedboat) from Nha Trang to the nearby Islands of the Hon Mun Marine Park.
Dive sites include:
- Bob's House. — 25 metres. Hard & soft corals.
- Debbie's Beach. — 15 metres. Outstanding hard & soft corals.
- Dopey's Ear. — 18 metres. Wall & pinnacles.
- Electric Nose. — 45 metre wall dive. Currents. Advanced only.
- Goat Rock. — Wall dive to 40 metres.
- Hamburger Hill. — 20 metres. Rocky pinnacle with soft corals.
- Hard Rock 1. — Wall & cavern dive to 25 metres.
- Hard Rock 2. — Wall dive to 15 metres. Hard corals.
- Hard Rock 3. — Wall dive to 20 metres. Hard corals.
- Hon Mot East. — 20 metres. Outstanding coral garden.
- Mama Hahn beach. — 18 metres. Hard corals.
- Madonna Rock. — 5-25 metres. Hard corals. Swim thru's.
- Moray beach. — 20 metres. Hard & soft corals. Giant morays.
- Rainbow Reef. — 20 metres. Outstanding hard & soft corals.
- The Range. — Wall dive to 25 metres with caverns.
- Seahorse Bay 1. — 15 metres. 'Muck diving'.
- Seahorse Bay 2. — 18 metres of 'Muck diving'.
- Tiger Wall. — Wall dive to 25 metres.
- Uta bay. — 15 metres. Sandy & rocky.
Marine life may not be as prolific as the Red Sea or the Great Barrier Reef, but the variety of species and vivid colours will fascinate and thrill divers and snorkellers, beginners and experienced alike! There are many varieties of fish including paperfish, devil scorpionfish, dragonettes, flying gunard, cowfish, giant moray eels, manta rays, large stingrays. There are also occasional turtles, and a variety of nudibranchs & other reef invertebrates. There are over 400 species of hard coral making it one of the richest hard coral dive regions in the world.
- Amigos Divers [www.amigos-divers.com]
- Angel Dive [www.angeldive.com]
Diving destinations in Europe include the more popular international destinations in the Mediterranean and mostly domestic destinations in the rest of Europe. Exceptions include some famous wreck dives at Scapa Flow in the Orkney Islands and the fjords of Norway
The wreck of the Zenobia off Larnaca is among the best and most easily accessed in Europe.
Diving in a crack between the continents in water as clear as it can get, being filtered by lava fields for decades.
- Sardinia — Also known as Sardegna, has a cave system in Alghero, with crystal clear water and astonishing limestone cliffs, it is one of the more significant cave diving destinations in the Mediterranean Sea. Red coral, lobsters, groupers.
Stunning limestone formations, steep dropoffs and good visibility make this one of the best diving destinations in the Mediterranean
Diving in Sweden often requires dry suit at all time of the year. The waters are dark and characterized by limited visibility. Although it is challenging it is known for the unique preservation of submerged objects (such as hundred years old wooden boats etc)
Dive sites include:
- Darkwood Reef
- Charlotte Reef
Dive sites include:
- Devils Table
- North West Point
- British Columbia — Cold water diving among wrecks with large sea life.
Maria la Gorda — popular scuba diving destination
Located in the center of the Caribbean island archipelago, Dominica's dramatic landscape is as spectacular underwater as it is above. Dominica is one of the top dive destinations in the world, and has been rated in Scuba Diving Magazine #1 for Marine Life, #1 for Healthiest Marine Environment, #1 for Small Creatures, and #3 Dive Destination.
Bay Islands of Roatan and Utila have a large dive community. Site include abundant sea life on varied terrain including wall dives. Warm waters, excellent visibility and low currents.
- Saint Pierre : Scuba dive at wrecks in the harbor. During the 1902 volcanic eruption, all but one of the ships in the harbor sank, leaving many wrecks as dive sites.
- Cabo San Lucas — on the southern tip of the Baja Peninsula is a meeting point of reef and blue water fish. While the number of dive sites are limited the variety of species makes up for it as do the viewing of the sand falls.
- Cozumel — has excellent and very accessible diving making it one of the most popular diving destinations in the northern hemispheres. The area is well known for reef, wall and drift diving as well as for a lively top-side scene.
- Yucatan — Cancun and Playa del Carmen are well known for cave diving and advanced diving in the labrynth of fresh water cenotes.
Dive sites include:
- Monkey Shoals
This small volcanic island is located south of Saint Martin and differs from other Caribbean islands as it features steep drop-offs and submerged pinnacles that are virtually untouched.
Dive sites include:
- Diamond Rock
- Outer Limits
- Tent Reef, Tent Reef Deep and Tent Reef Wall
- 3rd Encounter
- Man o' War shoals
- Torrens Point
- Twilight Zone
- Core Gut
- Shark shoals
- Green Island
- The John
- Hole in the Corner
Dive sites include:
- Ile Fouche
- Ile Chevreau
- La Baleine
Saint Christopher (St Kitts)
Dive sites include:
- Palmer’s Paradise(Turtle Canyons)
- Old Road Town Bay
- Sandy Point Bay
- Mystery Shoal
- Popeye’s Corner
Dive sites include:
- Hen and Chicks
- Moon Hole
- Cable Reef
- The Maze
- Proselyte Reef
- HMS Proselyte Wreck
- Florida — Reef diving off the Florida Keys and Cave diving in the extensive limestone cave networks.
- North Carolina — Wreck diving up to and beyond 130 feet deep. Sometimes referred to as the "Graveyard of the Atlantic" because of the numerous shipwrecks. Frequent opportunities to encounter Sand Tiger or Ragged Tooth sharks.
- California: Monterey, Channel Islands, Farallon Islands.
- Michigan: lake Michigan diving offers the most preserved shipwreck diving in the world.
The coastline of Australia is very long and includes a considerable range of water temperatures and marine ecologies.
- Great Barrier Reef -- large tropical reef system, most operators do sheltered easy diving. The reef is a few hours' boat ride from most of Far North Queensland. However the area has been over used and is in danger of being damaged beyond recovery.
Known for having extremely clear water. It is a great scuba diving and snorkelling destination.
- Saipan — Located at latitude of 15.25° north and longitude of 145.75° east, about 200 km (120 mi) north of Guam, Saipan is about 20 km (12.5 mi) long and 9 km (5.5 mi) wide. The island is a popular dive destination in the Pacific. The island is a typical middle-aged island composed of ancient fossil-rich coral limestone atop a subsiding, extinct marine volcano. A fringing reef of healthy offshore corals forming an extremely large lagoon and many small shallow lagoons in its larger bays, as well as a few offshore subsurface coral mounts. Saipan's excellent reefs, white beaches, clownfish colonies, underwater caves, WWII shipwrecks, underwater WWII munitions dumps, and underwater WWII plane wreck offer diving that appeals to almost every type of diver. Visibility, typically in the 50~90ft(16~30m) range, varies enormously based on location, tide, and season. Wave conditions are ideal, seldom rising above 1~2ft(30~60cm) in height, except during typhoons and tropical storms.
- Chuuk Lagoon — wreck diving, including optional penetration, on a huge number of ship and aircraft wrecks from World War II's Operation Hailstorm.
Madang — a town with fine scuba diving
Intermediate level wreck diving, including penetration, on the President Coolidge, blue hole diving with excellent visibility.
Brazil offers many destinations for diving:
- Fernando de Noronha marine park (Pernambuco state), famous for marine life but including shipwrecks
- The many shipwrecks of Recife (capital of Pernambuco)
- Arvoredo marine park (Santa Catarina state)
- Cavern diving at Bonito (Mato Grosso do Sul state)
- Cavern and cave diving in mine at Mariana (visiting Mina da Passagem) (Minas Gerais state)
- Abrolhos marine park and Salvador (Bahia state)
- Parcel de Manoel Luís (Maranhão state)
- Fortaleza (Ceará state)
- Maceió e Paripueira (Alagoas state)
- Guarapari (Espírito Santo state)
- Arraial do Cabo, Paraty and Ilha Grande (Rio de Janeiro state)
- Ubatuba and Laje de Santos (São Paulo state).
There are also liveaboards in the Northeastern region.
To dive in public parks (like Fernando de Noronha) one must be certified by one of the agencies recognized by IBAMA (Instituto Brasileiro de Administração do Meio Ambiente), a federal organ.
Colombia has some of the cheapest diving in South America. A cheap place to learn is Taganga.
- The islands of Isla Gorgona, San Andrés and Providencia have some really good diving.
- A little known but excellent location for large pelagics (i.e hammerhead sharks, whale sharks etc.) is Malpelo Island. It is accessible by live aboard only.
- Galapagos Islands - Darwin and Wolf Islands offer the opportunity to see schools of dozens of hammerhead sharks, while whale sharks and other large sea creatures are also frequently sighted.
It is best to learn diving from a competent instructor, as there are a number of skills important for your health and safety. It is an activity where there are a few things that must be done right or you may kill yourself. Experience and qualification of the instructor, while not a guarantee of competence, at least indicate that the instructor was trained and certified by an organisation which in some way strives for quality assurance, and allows some recourse if you are dissatisfied with the service. Aside from the complexities of assembling the equipment, diving has a number of risks that you need to understand, and safety procedures which you need to learn. There are also some basic skills that it is useful to practise under a teacher: the major one is controlling your buoyancy so that you aren't alternately sinking and floating but instead can swim along without yoyoing, and can ascend and surface at a controlled rate to avoid injury from rapid pressure changes.
Precisely because of these safety concerns, you will need to be trained and certified in order to get insurance for medical treatment you may need after a diving accident.
As a first-time diver, you will learn to dive in open water with no decompression. The term "open water" refers to dive sites from which you can swim straight up to the surface (not caverns, for example). "No decompression" diving is diving timed so that you do not have to ascend in stages and wait long periods of time at various depths to expel excess gas from your system, meaning that in an emergency you can go slowly but directly to the surface without an undue risk of decompression sickness.
Open water certification
Open water certification courses are complete beginner level diving courses: they assume no experience, but after passing the course you will be certified as being able to dive in open water with a similarly qualified buddy diver but without an instructor's company, at least in cases where conditions are similar to those in your course.
Open water certification is close to mandatory: many insurance companies demand either that you dive with an instructor or that you dive with open water certification in order to insure you and many dive tours will require that you are certified to at least this level before they will take you diving.
Open water courses tend to take three or four days full-time although you can often arrange to do them part-time or in pieces over a period of time. The time is divided between: time in a classroom learning the theory of diving; time in a pool learning how to use the equipment and move around underwater; and several dives in open water under the care of your instructor. Some certification agencies now offer the classroom syllabus online, and you only need to do the pool and open water dives with an instructor. Certification tends to be progressive: you need to pass each module in order to proceed to the next. It's usually the case that you pay for the course, not the certification: paying the money does not guarantee that you will pass the course. That said, beginner courses are not very challenging and, barring medical or psychological issues, nearly all participants pass.
Some people recommend that you do the open water certification before a holiday rather than during it: you will need to be prepared to spend holiday time for time in a classroom otherwise, and the time on the course will seldom be spent at the most interesting dive sites. However, many travellers do do their open water certification on holiday, either because they didn't plan to start diving until they arrived, they don't live near dive sites, or they have a particular location in mind where they want to spend their first dives. It is also usually possible to do a open water referral where you do classroom and pool training with one instructor and then do the required open water dives and finish your certification with another. This can be used to do the preparatory work at home and the dives on your holiday. You may need to do both halves of the course under the same certification agency's syllabus: check if your preferred agency is in the Universal Referral Program .
Other beginner courses
If you only want to dive once or twice, or you want to try it before you commit to a full certification, there are often shorter courses (known as resort courses) available. They are 'taster' courses in which you receive basic training in the equipment and do an open water dive under the supervision of an instructor. They are not complete certifications and do not fully train you to plan your own dives with a buddy; you will need the close attention of an instructor at all times. If you intend to dive more than a few times in your life, a full open water certification is worth the cost.
These supervised dives and courses vary widely in quality and safety. You should check that you will be diving in a very small group (or ideally one-on-one with a certified instructor as your personal dive buddy); that you will be diving at a shallow depth (no more than 12 meters/40 feet); and that the conditions are as tranquil as the area permits: cold water and currents are more stressful to dive in than still warm water.
Some certification agencies provide a syllabus for a resort-style course that will allow you to try an open water dive with a small amount of training and an instructor close by; for example PADI's "Discover Scuba" and "Scuba Diver" courses or SSI's "Try Scuba" and "Passport Diver" courses. These courses usually include part of the material for an open water certification, so that when you complete the short course you can go on to finish the open water course without needing to do the full course from the beginning.
Some dive resorts offer their own supervised diving or resort courses. If your resort certification is only awarded by that resort and not by one of the certification agencies then you will not be able to use it at most other resorts and it is unlikely to count towards a full certification.
There are a number of agencies which certify divers. They work by training and certifying instructors in their syllabus and teaching methods, and then allowing those instructors to certify individual divers. This section lists some of the certification agencies and their recreational (rather than professional or teaching) certifications. Your choice of certification will depend on a number of factors, primarily which certification agencies have a presence in the area you learn in, and in the areas you wish to dive in.
All reputable dive operators will require certification of your skills in the form of a certification card (C-card) from a recognized agency. This does not need to be the same agency that their own instructors work with: for example, a CMAS or SSI certified diver can dive with a shop that certifies under PADI. The requirement for certification is often also enforced where the customer wishes to buy Scuba equipment or have cylinders filled, but this is not universal, as in some countries there is no legal obligation for a recreational diver to be certified.
Recognised recreational certification agencies include:
- ACUC: The American Canadian Underwater Certifications 
- ANDI: American Nitrox Divers International,
- BSAC: The British Sub Aqua Club , bases its training on a network of affiliated clubs.
- CMAS: The French-based Confédération Mondiale des Activités Subaquatiques  , a volunteer-run amateur organization that takes a more comprehensive approach than many of the commercial agencies. There are national certification agencies affiliated to CMAS for most countries where training is done under their standards. Certification by all CMAS agencies is considered to be equivalent, but national agencies do not all necessarily provide the same range of certification.
- GUE: Global Underwater Explorers , concentrates on technical and cave diving specialities.
- IANTD: International Association of Nitrox Technical Divers.
- IDEA: The International Diving Educators Association 
- ISI: The Independent Scuba Instructors
- NAPI: The National Association of Professional Instructors, does not train directly, but issues certification based on recognition of prior learning and experience.
- NAUI: The National Association of Underwater Instructors , US-based, is the oldest recreational scuba certification agency.
- PADI: The Professional Association of Diving Instructors , the largest scuba certification agency, a commercial agency targeted towards recreational divers who want to learn quickly.
- PDIC: The Professional Diving Instructors Corporation 
- SDI/TDI: The Scuba Divers International/Technical Divers International  , a certification agency designed to train with an emphasis on practical diving skills. SDI focuses on the recreational side of scuba diving and TDI is the mother branch that specializes in Technical Diving.
- SSI: Scuba Schools International , another large commercial agency.
After completing a beginner level dive course, you can do additional courses to increase your skills or to pursue particular interests.
Post-beginner skills involve learning to dive in new or more difficult conditions or learning to dive using different equipment. There are several reasons you might pursue more skills in addition to the simple challenge: increased safety knowledge or a desire to dive at particular sites that need those skills are among them. Often you will need to do a formal course in new dive skills because centers running dives using those skills will require evidence that you are properly trained. Post-beginner skills that usually require training include: diving using oxygen enriched air ("nitrox"), deeper diving (optionally including decompression), wreck diving and cave diving. A diving rescue course is worthwhile if you dive regularly, whether or not you continue as a no-compression open water diver. Most certification agencies have courses in these skills and some wrap a number of them up into various 'Advanced' certifications. Many divers proceed to more difficult conditions (cool water, diving at night) without formal courses, but they are available if you want them.
In this context 'Advanced' implies only slightly more advanced than a complete beginner. The term should not be understood to mean any significant experience or skill level, as it can be achieved with very little experience and only slightly more than minimal skills. It is largely a marketing term, as beginner divers like the idea of an 'Advanced' certificate, and are more eager to pay for the training when this word is printed on their certification cards. A similar meaning (or lack thereof) is connected to the 'Master Scuba Diver' certification. In both cases the training and experience is valuable, and may even be worth the cost, but do not be misled about the reality. Divers with these certifications are advanced beginners until they have some range of experience.
Interests are particular reasons why you dive and include: underwater photography and videography; marine life identification; and marine life conservation. Many of the dive certification agencies have guided dives or courses in these fields but you may also be able to learn them informally from self-study, practise and fellow divers.
Finally, some divers are interested in mapping and describing dive sites. There are no formal courses or certification in this field, though some relevant trining may be included in Divemaster programs. If this turns out to be one of your interests, consider writing up your favourite sites on traveller-now, so that you can help the diving community by sharing your knowledge and experience. There are templates and guidelines on the currently recommended formats, but anything is generally better than nothing, so feel free to plunge forward and input your experience. If you want more guidance on this subject, refer to one of this article's docents.
There are three major types of travelling to your dive site: liveaboards where you stay on the boat, day trips where you take a boat trip out to your dive site and back in the same day, and shore diving where you get in from the land.
On a liveaboard
Many divers prefer liveaboards, where they sleep on the dive boat. This can save on accommodation costs, allow for more diving, and make it easy to get to know your fellow divers. Liveaboards range from 1 night in length to a fortnight or more. Liveaboards typically allow between 3 and 5 dives per day (depending on time and dive tables). The accommodation quality ranges from backpacker-esque, with 4-share cabins and showers shared between multiple cabins, to luxury cruise style accommodations. If you haven't opted for a luxury liveaboard, you will get your dives for about two thirds the cost of a day trip on a boat, even leaving aside any savings on accommodation.
When travelling on a liveaboard:
- pack as little as possible: a few changes of weather appropriate clothes, sleep gear, toiletries, light-weight entertainment (non-electronic is best) and your dive gear if you aren't renting
- space is always at a premium, and it's easy to get things mixed up and annoy fellow divers, keep your dive gear together in a tub or bag on the deck
- label your possessions with your name; they will be mixed up with a lot of similar looking equipment
- dry off before heading into the interior of the boat so that the floors aren't constantly wet
- most boats have a limited supply of fresh water for drinking and washing: have short showers
If you haven't spent much time on boats, you may not be aware of whether or not you get sea-sick. Some divers have an unhappy first dive trip on boats because they weren't aware that they suffer from sea-sickness. If you haven't been on a boat in open before, especially if you suffer from other kinds of motion sickness, you might be best off doing a few day trips on dive boats and experimenting with sea-sickness medication before committing to a liveaboard. That said, liveaboard trips for your first dives can be an excellent introduction, because you will usually do more than the bare minimum dives required for certification. Instead, you will get a lot of additional dive experience.
The main activity on a liveaboard is the diving: you will wake early for your first briefing and only complete the last dive at or after sunset, day after day. During the surface time you need to let nitrogen out of your body you will usually be eating or sleeping. Liveaboard trips are excellent for dedicated divers, but may not suit divers who don't want to spend their entire holiday gearing up, diving, getting their gear off, eating and sleeping.
On a day trip
Many dive sites are accessible by a boat ride of a few minutes to a few hours from shore, so you can go out to the site on a boat, dive and return to your land-based accommodation at night. Boats which conduct day trips range from rubber dinghies equipped with an outboard motor to larger boats with indoor areas and hot showers. Longer day trips tend to entail nicer boats. Dive trips that take much of a day will usually include a catered lunch and perhaps some smaller snacks in the price. On a per-dive basis day trips are usually more expensive than liveaboards, so divers choose to day-trip when they want to only have a few dives at a particular set of sites, or when they want to alternate diving with other activities.
As with liveaboards, some people take their first boat trip unaware of the possibility of sea-sickness. If you think you're at all likely to suffer (ie if you get sick in cars or other vehicles), you should take some preventative measures an hour before leaving on the boat.
Be aware that not all day trip boats will have toilet facilities. Since it's not a good idea to dehydrate yourself before diving you may have to accept that you will have to urinate either over the side of the boat or into a bucket which you'll tip over the side and rinse. This can be a little more difficult for women to do quickly and safely. If this is unacceptable to you be sure to check on the boat's facilities in advance.
Some day trips are organised by dedicated dive resorts, which bundle day trips and land based accommodations into one price. You usually won't be compelled to stay with them in order to do their trips, but it may be cheaper. During peak times you may need to dive on most days of your stay to take advantage of the deal.
Shore-based dives are dives where the site is close enough to the water's edge that a diver can swim out into the water and descend to the dive site. Shore diving is cheaper than boat diving: unless you're paying an instructor or guide you only need to pay for any equipment you want to hire. You will often find a dive shop or dive resort conveniently located near a good shore dive site.
Shore diving can be tiring if the site is not extremely close to the shore. Rescues may not be as fast as from a boat which will have spotters looking out for divers in distress. Be sure to check the length of the swim to your chosen site and its difficulty: shore dives are not necessarily easier than boat dives.
Some shore dive sites are either only accessible, or are much safer and easier dives, at a certain tide height. Unlike on a boat dive, where the boat operator can time the visit to correspond to the right tide if need be, shore divers need to find out about tidal sites and tide times themselves. It's also not impossible to get sea-sick on a shore dive, particularly if swimming or resting on a choppy surface. It's easier to avoid though as most people find that dropping below the surface where there is less motion helps or removes the nausea.
Different dive sites have different things to offer:
- Many divers dive in order to see marine life. Particular favourites include turtles, mantas and especially sharks. The fascination with sharks can sometimes escape non-diving friends but most species of shark don't pose a threat to divers and they are beautiful to watch. Diving with a whale shark is one of the most highly prized diving experiences. Others develop an interest in reef life, including the enormous range of invertebrates that live on the bottom, and the often colourful fish that live around them.
- Divers interested in marine life or just in new experiences like to dive at night. Nocturnal marine life is different, and sometimes more active, than daytime marine life. Night diving does not require added equipment above daytime diving other than a powerful torch, and is often one of the first new experiences available to newly certified divers. Often the use of artificial light will bring out an intensity of colour that goes unnoticed during the day, when the water absorbs much of the colour at depth.
- Tropical coral reef diving surrounds you with a sometimes unbelievable amount of colour and activity. Diving in tropical water is also comfortable and often low stress because the water is very clear. You are vulnerable to stings and to nasty coral scratches which are easily infected though: many divers choose to wear a full length thin wetsuit even if the water is warm enough to dive naked!
- Rocky reefs occur in tropical, temperate and polar waters, and support ecosystems which may range from quite similar to coral reefs, to considerably different. In many regions on rocky reefs, instead of colourful fish, the rocks are encrusted with sponges, soft corals, colonial ascidians, bryozoans and a wide range of mobile invertebrates, which together contribute to an overall effect as colourful as a tropical reef.
- Wrecks have three appeals: fish life, historical interest and technical difficulty. Wrecks that have been sunk for some time become artificial reefs, attracting fish life and coral. The trade-off is that this tends to happen in warmer water, which will also cause the wreck to disintegrate more rapidly. Wrecks in colder water will attract less marine life but retain historical interest, particularly those of ships that were lost at sea rather than stripped of artefacts and scuttled. Wrecks of planes, particularly those shot down in wartime, are also popular. Divers can actually enter some wrecks: however this is relatively hazardous and requires training and experience well beyond introductory open water training.
- Caves have an appeal to some divers, who enjoy the feeling of going where few people have ventured, and some caves provide spectacular surroundings. This environment is inherently hazardous and requires training and experience far beyond introductory open water certification.
- Many divers enjoy underwater photography or underwater videography. To take pictures or video while diving, you will need a waterproof housing for your camera or video recorder. Many dive shops also have rentable cameras.
Scuba diving equipment has standardised into a number of basic pieces, together with some optional pieces for certain conditions. Most dive centers will have all the standard equipment for rental, and as with many equipment-heavy sports it can be worthwhile to use rental equipment for a while before you decide to purchase your own.
Standard equipment is:
- A mask which provides an air space over the eyes and nose with transparent viewport which may include corrective lenses. This allows you to focus and see clearly under water.
- A snorkel (a short curved tube with a mouth grip allowing you to breathe at the surface with your face underwater)
- Fins for propelling yourself underwater
- An exposure suit: a wetsuit for warm water or a dry suit for colder water, perhaps with boots, gloves and hood. A skin suit is a very thin wet suit which is mainly intended as protection from stings, scratches, chafe and sunburn in tropical water.
- A Buoyancy Control Device (BCD): an inflatable jacket or back inflation "wing" allowing you to sink or float by deflating and inflating it, and to neutralise buoyancy at any depth so that you can stay there without effort. This usually includes the support for the Scuba cylinder, and a harness system of straps and buckles by which it is secured to the diver.
- A compressed air tank to supply breating air during the dive.
- A regulator: apparatus for delivering air from the tank to your mouth on demand at ambient pressure.
- A weight belt, weight harness or weight pouches integrated with the BCD, to compensate for the buoyancy of the exposure suit.
- A depth gauge
- A Submersible Pressure Gauge (SPG), which shows the pressure of air remaining in the tank.
- A timing device
Optional equipment includes:
- A dive computer to record depth and times and to indicate decompression requirements. It is usually used to avoid the requirement for decompression stops.
- Tanks and regulators for breathing gas mixtures such as Nitrox (air enriched with additional oxygen), Trimix (a mixture od Helium, Oxygen and Nitrogen which reduces nitrogen narcosis) and pure oxygen (for accelerated decompression)
- Underwater photography or videography equipment. Disposable 'waterproof' cameras and cheaper underwater housings are generally only guaranteed to be leak free to about 3 meters/9 feet in depth, you will want one waterproof to at least 30 meters/100 feet. Properly rated housings are manufactured by many major camera manufacturers, and for more expensive cameras and video cameras housings are made by third parties.
Check the warranty conditions carefully, especially on expensive electronic equipment: water damage is usually not covered even on the housing warranties. Specialist dive insurance may provide insurance against loss of or damage to your equipment while diving, general travel insurance usually will not, even if it covers the medical aspects of diving.
Rent or buy?
The three pieces of equipment every diver should buy for themselves and bring along are fins, snorkel and mask: these need to fit to your body closely to be safe and comfortable, they're fairly cheap, and they don't need that much space. Up next is an exposure suit (wetsuit or drysuit), which is also better fitted than off the shelf, but is bulkier to carry along. Rental wetsuits are generally adequate in warm waters if you are close to average in size and build.
But the bigger question for most divers is whether they should also make an investment in a full set of scuba gear, namely regulators, gauges and BCD. In purely financial terms, you have to dive quite a bit to save money this way, especially when you factor in yearly servicing fees. However, perhaps a bigger factor is safety: not only can you ensure that your own gear is kept properly serviced, but you will already be familiar with the controls and performance of your own gear, which makes diving easier and increases the chances of you acting correctly in an emergency. A personal regulator set and dive computer are recommended for the serious diver.
The two items almost nobody brings along are tanks and weights, as these are extremely heavy and bulky, and practically always included in the dive price. For some destinations well and truly off the beaten track though (say, the Red Sea coast of Sudan) you may have to take along not just these, but the compressor too!
The recreational scuba diving industry in popular diving areas is usually partly staffed by travellers, mostly divers themselves funding their diving.
In order to actually be paid to dive in the recreational scuba industry, you will need to either be a certified divemaster or an instructor. Divemasters look after paying divers on the boat, handle any problems they have and tell them about the dive sites. They might also lead underwater guided tours of dive sites and assist in diving classes. Instructors run the diving classes themselves. You train as a divemaster first and then qualify for instructor training.
Divemaster and instructor certifications are awarded by the same agencies that award the other recreational diving certification. To enter the instrictor training programmes you will generally need to be a skilled diver and have at the barest minimum somewhere in the order of 100 dives experience. Many instructors trainers recommend a great deal more experience before starting. Divemaster and instructor certifications are expensive to gain and expensive to keep, as you will need to renew them and also may have to pay an insurance premium.
Other work available to travellers in the diving industry includes retail, boat operating and repairing, dive equipment maintenence and cooking. If you're travelling out on dive boats you will often be expected to be able to dive, and possibly to hold diver rescue and first aid certifications, even if you're notionally the cook. For both diving and boat work, some experience in hospitality is valuable, although not always necessary.
Almost all diving work, especially in extremely popular tropical diving locations, is badly paid. In some countries, divemasters are expected to work for tips alone. You will generally make enough to cover the basic expenses of a backpacker lifestyle and will usually get some free diving (although not as much as you expect).
In some countries any commercial (paid) underwater work other than that directly connected to recreational diving is regulated by legislation. In many cases this will require the working diver to be registered as a commercial diver and to comply with health and safety regulations. Check the local situation before taking on any such work, as although it will often get by under the radar, it may be technically illegal and if anything goes wrong the foreigner is usually the scapegoat. In other countries there may be no laws at all controlling underwater work, however these are usually also the countries where standards of safety and protection of the worker are likely to be lowest.
The obvious safety concern with diving is that you must rely on your equipment to deliver you air. For this reason, scuba equipment is subject to rigorous testing according to various standards at the design and production stages. Your part of ensuring your own safety is making sure that you are adequately trained and prepared for any dive you do, and that your equipment is suitable for the dive and functioning correctly. Do not assume that rental equipment is in good order: test it yourself.
The other side of this is to ensure that the air you breathe is safe. Most popular diving destinations will provide air fills from a suitable compressor in good condition and adequately filtered. Other places may be more haphazard and compressors that are in bad condition, dirty filters, poor installations, external sources of contamination and careless or unscrupulous operators may provide you with contaminated air. Contamination at levels which may be imperceptible or merely give you a headache or mild nausea on the surface can cause loss of conciousness underwater, often leading to drowning.
Being familiar with symptoms of equipment failure and recovery techniques obviously improves your safety. Your training will include information about performing basic safety checks on your equipment and about other guidelines. Further training is available in specialty courses.
If you're diving regularly you will probably want to take courses in emergency diving procedures and in first aid including CPR.
Basic safety precautions
The basic precautions you should take for safe diving are:
- Have an agreed plan for every dive, including where you expect to go, how you will manage your air supply and what you and others will do if something unexpected happens (common problems are getting low on air, getting lost or losing your buddy)
- Do not dive alone, always dive with a partner (a "buddy") who will stay close to you. Typically regulators have a second mouthpiece you can lend a buddy if they are out of air. Remember that a buddy who is not in reach in an emergency or who is not competent or willing to assist is no buddy at all, and that a buddy has no legal obligation to assist if it may endanger him or herself to do so. Do not allow the dive operator to pair you with someone whom you could not assist or who would not be able to assist you.
- Do not dive in unfamiliar conditions without an orientation from a suitably competent person, or you may find your skills are not adequate to the task. This is a common problem for divers who are accustomed to warm, calm water and find themselves under stess the first time they dive in cold rough water, or in a current.
- Do not dive in unfamiliar areas without a guide or appropriate orientation. Do some introductory dives or a dive orientation with a divemaster or diver with local experience.
- Do not dive outside your training and experience, for example, diving deeper than you trained for, or diving in confined spaces when you're only certified for open water.
- Do not dive with unfamiliar equipment except in very easy conditions, where any problems can be sorted out without major inconvenience or risk. Get your weights sorted out in shallow water, make sure the regulator has no leaks, and that the harness fits properly before going on a deep dive. Many divers have no idea of how much weight they will need with an unfamiliar exposure suit, and almost none will get it right first time.
- Do not dive when impaired, e.g. by fatigue or alcohol.
- If diving in a group led by a guide, do not neglect your own planning and air management and if necessary plan to ascend early without the guide. Divemasters vary in skill, but even the best will not substitute for taking responsibility for yourself.
- If you feel overly anxious about the dive, or feel you may not be fully qualified for the conditions, you have the absolute, unconditional right to end the dive without having to justify your decision. Ultimately, you are responsible for deciding if any particular dive is right for you.
- Check the air you will be breathing. It should have no smell or taste and should leave no mark when passed through a white cloth. These tests, if passed, do not guarantee that there are no contaminants, but if failed, dont breathe it. If you have any doubt, ask the shop to show you the latest air quality test results. Some places may not require this to be available, in which case a look at the compressor installation can tell you a lot. If the operator refuses to give this information, decide for yourself whether it is a good idea to stake your life on their product. Some countries have legal standards for minimum breathing air quality. These include USA, Canada, EU countries, South Africa, Australia and New Zealand. Some other countries do not. Portable testing equipment is available for the most important contaminants, but it is quite expensive. It is a matter of what your life is worth to you, and what risks you accept. When booking, ask about air testing and quality control.
- Dive with reputable and competent operators. Find out beforehand what the qualifications are of their skippers and divemasters, and what emergency facilities are available. You can still choose to dive with a less than ideal operation, but it is then an informed choice. Litigation after the accident is a waste of time and money in some parts of the world.
Checklist on potential dive operators
A few questions you could ask the dive operator before booking when planning a dive vacation to an unfamiliar region.
- What are the qualifications of the skipper and divemaster?
- Is a member of the crew qualified in basic first aid and oxygen administration.
- Do they have emergency oxygen administration equipment on site and on the boat?
- What is the local air quality standard, and how is it enforced?
- How are seaworthiness of the dive boat and competence of the crew enforced?
- What emergency facilities are available in case of an accident?
- Search and recovery.
- Medical evacuation.
- First aid.
- Medical treatment facilities.
- How do they monitor the time that a diver has been off the boat and whether all the correct divers are back on board before leaving the site?
Standards for these items vary enormously. Do not assume that they will be much the same as at home. Oxygen is unavailable some places, and there are countries that do not have any recompression facilities at all. The last item may look a little trivial, but even in countries where safety standards are taken seriously, divers are occasionally left behind by accident, and it has happened that the right number of divers were on the boat, but some of them had dived from another boat, so a simple head count is not always sufficient.
Many dive sites are ecologically or historically sensitive areas. Dive tourism has the advantage of providing a reason to preserve many sensitive sites in order to keep the divers coming: for example, dive tourism may provide an incentive to control overfishing on divable reefs. However divers do themselves present a threat to many sites, having the potential to either directly damage them or subtly influence their characteristics. In order to help preserve dive sites:
- Look but don't touch, be it the bottom, coral, marine life or wrecks.
- Don't take souvenirs as everything you take is one less thing for future divers to look at, and often one less home for sea creatures. This is also illegal in some areas in the case of both protected marine sanctuaries and wrecks.
- Learn good buoyancy control, so that you can avoid accidental damage to the site from crashing into things
- Don't feed the fish, as it alters their natural feeding patterns, and if you get bitten while feeding fish, no-one will have any sympathy.
Some dive organizations promote a diving variant of the leave no trace motto: "take nothing but photographs, leave nothing but bubbles."
Health conditions which prevent diving
Any medical condition which affects your respiratory or cardiovascular systems, or which may render you suddenly and unexpectedly unable to respond quickly or at all, might mean you cannot dive. Common contraindications are asthma, epilepsy, diabetes and heart disease. If you have any of these, or other illnesses which might cause similar problems, consult a doctor before diving. A physician with a knowledge of dive medicine and diver needs is best, particularly if you have a condition like asthma and want an informed opinion about whether your particular case means you can't dive.
Most dive courses will require a detailed medical history from you or a doctor before you begin diving.
Other health conditions which may temporarily prevent you from diving safely include:
- Drugs and medications (consult a diving medical specialist if in doubt)
- Alcohol and recreational drugs
- Nervous system disorders
- Some cancers
- Hepatitis, Malaria, and any illness causing fever or significantly impaired strength, judgement or cardivascular condition.
With some, it is the condition itself, and others, it is the drugs that are given for the condition that exclude one from diving. Unfortunately, the medical profession doesn't give black and white answers and some of the conditions require the diver to accept the risk and responsibility for the decision. Research is being conducted by various agencies around the world all the time and official medical opinion and policies do change from time to time.
Pressure related illnesses
In scuba diving, air is delivered to your lungs at the surrounding water pressure. Breathing air at high pressure can contibute towards a number of illnesses:
- lung overexpansion in which high pressure air trapped in your lungs expands as you ascend, damaging your lungs and possibly forcing air into your bloodstream (an arterial gas embolism)
- decompression sickness ("the bends") in which dissolved nitrogen in your body forms gas bubbles as you ascend, blocking blood supply to limbs or organs
- nitrogen narcosis in which nitrogen causes impairment similar to drunkenness
- oxygen toxicity in which an excessive partial pressure of oxygen poisons your nervous system or lungs
All of these illnesses and their prevention will be discussed during diver training. Not all of them are fully preventable, hence you must be alert to the risk and know how to seek appropriate treatment. Always know how to contact the local emergency services and the diver emergency services (if they exist) before a dive.
Preventing dive-related illness
In addition to observing the time, depth and ascent rate limits you will be taught in training, there are some other things you can do to lower the chances of a pressure related illness. Before a dive trip and when diving , it is wise to:
- Be well hydrated. Dehydration is not only a health concern in and of itself, but is also a contributing factor to many cases of decompression sickness.
- Limit your alcohol intake, partly because of its intoxicating effects and partly because it dehydrates you.
- Avoid diving with blocked sinuses as high pressure air that enters them during the dive may not be able to exit, causing a painful "reverse block" that may take days to clear.
- Avoid ascending to a higher altitude soon after diving; in particular, do not fly in most aircraft (commercial aircraft included) as they are rarely pressurised to sea level. It is recommended that you wait at least 12 hours after a single dive with no decompression stop before ascending, 18 hours after multiple dives without decompression stops, and more time again if there were decompression stops. Ascending sooner puts you at risk of decompression sickness.
There are several scuba emergency telephone hotlines set up in different areas of the world, which can advise on your symptoms and sometimes organise rescues and treatment (however, you will still have to pay for both, unless covered by insurance). Keep a note of your local hotline among your dive gear.
Diving in high altitude lakes
While diving at high altitude lakes, the risk for decompression sickness increases. Due to a lower atmospheric pressure in the environment, special dive tables should be used. These allow for the pressure difference correction factors to avoid decompression sickness.
Preventing sea sickness
A substantial number of boat divers will experience some sea sickness. You are probably more vulnerable if you experience other forms of motion sickness, eg getting sick in cars. Sea sickness, because of the many ways in which the boat can move, is usually more severe than car sickness. The upside, such as it is, is that as under the water is much calmer than the surface almost all sufferers find that their nausea vanishes within a few minutes of beginning to dive. If you are feeling ill but able to get your gear together, you should still be able to have a good dive.
Sea sickness can be prevented for many people with the use of travel sickness prevention medication from pharmacists. Meclizine and dimenhydrinate (US brand name Dramamine) are commonly used for prevention of seasickness, but both have the dangerous side effect of making you drowsy, and the effect seems to be amplified underwater. Try them out before you dive, so you can judge your own reaction, and consider taking only half a dose. Alternatives include scopolamine patches (also known as hyoscine or "transderm scop"), which are very effective but often require a prescription; cinnarizine (Sturgeron), which is popular in Europe but poorly available elsewhere.
If your sea sickness is mild, you may be better off using natural remedies like ginger or simply staying near the centre of the boat, avoiding unnecessary motion, and looking at the horizon. However, severe nausea is extremely uncomfortable and vomiting will dehydrate you: if you suffer sea sickness this badly, or think you are likely to, you might find that the side effects are much easier to deal with than the nausea. On the other hand, most divers find that sea sickness is quickly relieved once the dive has started and you've escaped the choppy surface, and even if worst comes to worst, it's entirely possible to vomit through your regulator.(Do remember to purge well before taking your next breath).
If you are taking medication to prevent sea sickness, you should begin taking it well before you get on the boat so that it can be absorbed by the time the motion begins. Taking it an hour before boarding is effective; this will also give you some time to adjust to any drowsiness. Divers taking overnight trips sometimes begin taking medication the night before departure.
A boat briefing will often include instructions on what to do if you think you're likely to vomit. If these aren't given and you forget to ask, the general etiquette is to go downwind (usually the rear of the boat) so that it doesn't blow into anyone's face, and to the opposite side to the ladder, and vomit overboard. Ask someone to accompany you so that they can make sure you're safe and won't fall overboard.
There are some injury risks that diving exposes you to. This is dependent on the site. For example, coral reef dives carry the risk of coral cuts, which can take months to heal well, and of stings and bites from venomous marine life. Educate yourself about risks in particular environments and particular sites and pay attention to dive briefings.
You can dramatically reduce the risk of injury by exercising caution and not interfering with the state of the dive site (e.g. by provoking the marine life or disturbing the bottom). Assume that everything is dangerous (poisonous, sharp, aggressive, etc.) and you'll keep yourself out of harm's way by not being tempted to touch anything.
One of the functions of the exposure suit is protection from external injury. Thick and strong suits will protect against cuts from coral, barnacles, or sharp edges of wrecks, thinner suits will protect against jellyfish, fire coral and similar organisms.
It is very important to be insured for both general medical treatment needed for dive related illnesses and injuries, and in particular for decompression sickness treatment, which involves some hours in a recompression chamber. Recompression can be extremely expensive, around US$6000 an hour, and is specifically excluded by some insurance policies. In addition you should be insured for evacuation, as evacuation from boats by the emergency services is typically conducted from the air and is also very expensive.
There are many dive insurance policies which cover medical treatment needed after diving, including recompression. Some are associated with the certification agencies or with dive resort organisations. Typical prices are about US$500 per year for insurance for dives to less than 40 meters and US$1200 per year for coverage to any depth you have trained for. In addition dive resorts and dive tour operators will often have insurance for divers who are injured or become ill on dives they conduct.
Many general travel insurance policies cover diving if you are certified or with an instructor, but check the terms first: some also exclude scuba diving.