The following outline is provided as an overview of and topical guide to underwater diving:

Two divers wearing lightweight demand helmets stand back-to-back on an underwater platform holding on to the railings. The photo also shows the support vessel above the surface in the background.
Surface-supplied divers riding a stage to the underwater workplace

Underwater diving – as a human activity, is the practice of descending below the water's surface to interact with the environment.

What type of activity is underwater diving?

Underwater diving can be described as all of the following:

Diving activity, by type

Modes of underwater diving

Surface-supplied diver with helmet, bailout set and umbilcal cable

There are several modes of diving distinguished by the equipment and procedures used:

Diving skills and procedures

Technical divers at a midwater decompression stop
Divers decompressing in the water at the end of a dive
Divers doing a buddy check
Sidemount diver pushing a cylinder in front
Solo diver surveying dive site. The bailout cylinder can be seen slung at the diver's left side.

Diving procedures – Standardised methods of doing things that are known to work effectively and acceptably safely

Underwater diving, by environment

Ice Diving – View from the top

Underwater diving environment – The underwater environment to which a diver may be exposed

Occupational diving

Diver wearing a diving helmet is welding a repair patch on a submarine
Underwater welding.
NAUI Nitrox diver certification card
Pearl diver in Japan
Nesconset fire department scuba rescue team on training exercise
Salvaging a ship's propeller
Diver wearing a diving helmet is sanding a repair patch on a submarine
A diver at work on hull maintenance
Sponge diver putting on his diving suit in Tarpon Springs, Florida.

Professional diving, also known as Occupational diving – Underwater diving where divers are paid for their work, or dive as part of their occupation

Recreational diving

Diver returning from a 600 ft (183 m) technical dive
Two underwater hockey players competing for the puck
Underwater photographer
Divers on the wreck of the Zenobia

Recreational diving – Diving for the purpose of leisure and enjoyment, usually when using scuba equipment

Diving and support equipment, tools and weapons

Small high-pressure breathing air compressor
A small scuba filling and blending station supplied by a compressor and storage bank
Hydrospace Explorer Trimix and rebreather dive computer. Suunto Mosquito with aftermarket strap and iDive DAN recreational dive computers
Three representative wrist-mount dive computers
International code flag Alpha indicates that a diver is underwater nearby
A closed bell used for saturation diving
Lifting bag used to move a heavy object underwater
The Newtsuit atmospheric diving suit
US Navy Diver using Kirby Morgan 37 diving helmet
Helmeted diver entering the water. He has a back mounted Draeger DM40 rebreather system in addition to the surface supply air hose
Scuba diver with bifocal lenses in half mask
A diver wearing an Ocean Reef full face mask
U.S. Navy divers in dry suits prepare to dive
Two men operating a rotary diver's air pump

Diving equipment

Diving equipment – Equipment used to facilitate underwater diving

Autonomous underwater vehicles

Autonomous underwater vehicle – Unmanned underwater vehicle with autonomous guidance system

Breathing gas

Breathing gas – Gas used for human respiration

Decompression equipment

Decompression equipment – Equipment used by divers to facilitate decompression

Diver propulsion vehicles

Diver propulsion vehicle – Powered device for diver mobility and range extension

Diving safety equipment

Diving safety equipment – Equipment used to facilitate underwater diving

Historical diving equipment

Rebreathers

Rebreather – Portable apparatus to recycle breathing gas

Remotely operated underwater vehicles

Remotely operated underwater vehicle – A tethered underwater mobile device operated by a remote crew

Underwater breathing apparatus

Underwater breathing apparatus – Equipment which provides breathing gas to an underwater diver

Diving support equipment

Diving support equipment – Equipment used in the support of an underwater diving operation

Underwater work tools and equipment

Soviet SPP-1 underwater pistol
Airlift dredging
ROV at work in an underwater oil and gas field. The ROV is operating a subsea torque tool (wrench) on a valve on the subsea structure.

Underwater work tools and equipment – Tools and equipment used for underwater work

Underwater weapons

Underwater weapons – Weapons that are intended for use underwater

Science of underwater diving

Physics of underwater diving

Views through a flat mask, above and below water

Physics of underwater diving – Aspects of physics which affect the underwater diver

The diving environment

Plunging breaker
Lago Licancabur, site of world's highest ever altitude dive.
Entrance to Peacock Springs Cave System

Underwater diving environment – The underwater environment to which a diver may be exposed

Physiology of underwater diving

Diagram of the human circulatory system
Decompression profiles based on the Thermodynamic model compared with the US Navy table for the same depth and bottom time
Diagram of the human respiratory system

Human physiology of underwater diving – Influences of the underwater environment on the physiology of human divers

Diving medicine, disorders and treatment

Oxygen therapy in a multiplace hyperbaric chamber is often delivered via built in breathing systems.
Monoplace chambers can be used for hyperbaric oxygen therapy if the patient is stable

Diving medicine

Diving medicine – Diagnosis, treatment and prevention of disorders caused by underwater diving

Diving disorders and treatment

Mask squeeze - a mild form of barotrauma
Staged image showing how victims may black out quietly underwater, often going unnoticed.

Diving disorders – Physiological disorders resulting from underwater diving

Diving safety related articles

A dive team listens to a safety brief from their dive supervisor
Early testing for oxygen toxicity in divers
Tags in place in a powerplant after it was shut down
Folding lockout hasp, allowing six padlocks to lock out one device.
Checklists reduce the risk of omitting a step in a procedure

Diving safety

Diving safety – Risk management of underwater diving activities

Notable diving incidents rescues and fatalities

The decompression chamber at the moment the Byford Dolphin accident occurred. D1–D4 are divers; T1 and T2 are dive tenders.

Legal aspects of diving

Legal aspects of diving – how underwater diving and divers are affected by law

Geography of diving

Main article: Outline of recreational dive sites

Recreational diver over a coral reef in the Red Sea

Recreational dive sites are specific places that recreational scuba divers go to enjoy the underwater environment or for training purposes. They include technical diving sites beyond the range generally accepted for recreational diving. In this context all diving done for recreational purposes is included. Professional diving tends to be done where the job is, and with the exception of diver training and leading groups of recreational divers, does not generally occur at specific sites chosen for their easy access, pleasant conditions or interesting features.

Recreational dive sites may be found in a wide range of bodies of water, and may be popular for various reasons, including accessibility, biodiversity, spectacular topography, historical or cultural interest and artifacts (such as shipwrecks), and water clarity. Tropical waters of high biodiversity and colourful sea life are popular recreational diving vacation destinations. South-east Asia, the Caribbean islands, the Red Sea and the Great Barrier Reef of Australia are regions where the clear, warm, waters, reasonably predictable conditions and colourful and diverse sea life have made recreational diving an economically important tourist industry.

Recreational divers may accept a relatively high level of risk to dive at a site perceived to be of special interest. Wreck diving and cave diving have their adherents, and enthusiasts will endure considerable hardship, risk and expense to visit caves and wrecks where few have been before. Some sites are popular almost exclusively for their convenience for training and practice of skills, such as flooded quarries. They are generally found where more interesting and pleasant diving is not locally available, or may only be accessible when weather or water conditions permit.

While divers may choose to get into the water at any arbitrary place that seems like a good idea at the time, a popular recreational dive site will usually be named, and a geographical position identified and recorded, describing the site with enough accuracy to recognise it, and hopefully, find it again. (Full article...)

History of underwater diving

Siebe's improved design in 1873.

History of underwater diving

Frogman operations

Italian Maiale manned torpedo "Siluro San Bartolomeo" displayed at the Royal Navy Submarine Museum, Gosport, UK.

Notable underwater salvage operations

Salvage of Royal George

Diver training, certification, registration and standards

Commercial diver training at Blue Rock Quarry

Diver training

Diver certification organisations

List of diver certification organizations – Agencies which issue certification for competence in diving skills

Organisations setting international standards and codes of practice for diving and diver training

Commercial diving schools

Underwater diving organisations

Diver membership organisations

Diver membership organisations

Diver nature conservation organisations

Diving industry trade associations

Underwater environmental research organisations

Diving medical research organisations

Underwater diving publications

Books and manuals

Legislation

Codes of practice

(National or international codes of practice for diving)

Standards

(National or international standards relating to diving equipment or practices)

Breathing apparatus

Swim fins

Swim fin sole showing compliance with German standard DIN 7876:1980
GOST 20568:1975 compliant Russian and Ukrainian diving masks

Diving masks

A range of 1970s snorkels made to British Standard BS 4532:1969

Snorkels

Buoyancy compensators

Wet suits

Dry suits

Depth gauges

Diver training

Recreational diving practices

Journals and magazines

Repositories

Recreational dive site guides

Notable dive site guides with Wikipedia article.

Authors of publications about diving

Bob Halstead

Authors of general non-fiction works on diving topics who are the subjects of Wikipedia articles.

Documentaries

Documentary movies focused on underwater diving.

Underwater diving in popular culture

Movies, novels, TV series and shows, comics, graphic art, sculpture, games, myths, legends, and misconceptions. Fiction in general relating to all forms of diving, including hypothetical and imaginary methods, and other aspects of underwater diving which have become part of popular culture.

Researchers in diving medicine and physiology

John Scott Haldane c. 1910
Paul Bert

Underwater divers

This is a list of underwater divers whose exploits have made them notable. Underwater divers are people who take part in underwater diving activitiesUnderwater diving is practiced as part of an occupation, or for recreation, where the practitioner submerges below the surface of the water or other liquid for a period which may range between seconds to order of a day at a time, either exposed to the ambient pressure or isolated by a pressure resistant suit, to interact with the underwater environment for pleasure, competitive sport, or as a means to reach a work site for profit or in the pursuit of knowledge, and may use no equipment at all, or a wide range of equipment which may include breathing apparatus, environmental protective clothing, aids to vision, communication, propulsion, maneuverability, buoyancy and safety equipment, and tools for the task at hand. (Full article...)

Pioneers of diving

Jacques Cousteau

Underwater art and artists

Christ of the Abyss at San Fruttuoso, Liguria

Miscellaneous

Awards and events

See also

References