Underwater diving
Encyclopedia
- This article refers to underwater diving by humans. For other uses of the term diving, see dive (disambiguation) and divingDivingDiving is the sport of jumping or falling into water from a platform or springboard, sometimes while performing acrobatics. Diving is an internationally-recognized sport that is part of the Olympic Games. In addition, unstructured and non-competitive diving is a recreational pastime.Diving is one...
Underwater
Underwater is a term describing the realm below the surface of water where the water exists in a natural feature such as an ocean, sea, lake, pond, or river. Three quarters of the planet Earth is covered by water...
, either with breathing apparatus (scuba diving
Scuba diving
Scuba diving is a form of underwater diving in which a diver uses a scuba set to breathe underwater....
and surface supplied diving
Surface supplied diving
Surface supplied diving refers to divers using equipment supplied with breathing gas using a diver's umbilical from the surface, either from the shore or from a diving support vessel sometimes indirectly via a diving bell...
) or by breath-holding (free-diving
Free-diving
Freediving is any of various aquatic activities that share the practice of breath-hold underwater diving. Examples include breathhold spear fishing, freedive photography, apnea competitions and, to a degree, snorkeling...
).
Recreational diving
Recreational diving
Recreational diving or sport diving is a type of diving that uses SCUBA equipment for the purpose of leisure and enjoyment. In some diving circles, the term "recreational diving" is used in contradistinction to "technical diving", a more demanding aspect of the sport which requires greater levels...
is a popular activity (also called sports diving or subaquatics). Professional diving (commercial diving or diving for financial gain) takes a range of diving activities to the underwater work site.
Levels of training
Diver training
Diver training is the process of developing skills and building experience in the use of diving equipment and techniques so that the diver is able to dive safely and have fun....
and types of equipment and breathing gases used differ between types of diving.
History
Underwater diving for commercial, rather than recreational purposes may have begun in Ancient Greece, since both PlatoPlato
Plato , was a Classical Greek philosopher, mathematician, student of Socrates, writer of philosophical dialogues, and founder of the Academy in Athens, the first institution of higher learning in the Western world. Along with his mentor, Socrates, and his student, Aristotle, Plato helped to lay the...
and Homer
Homer
In the Western classical tradition Homer , is the author of the Iliad and the Odyssey, and is revered as the greatest ancient Greek epic poet. These epics lie at the beginning of the Western canon of literature, and have had an enormous influence on the history of literature.When he lived is...
mention the sponge as being used for bathing. The island of Kalymnos
Kalymnos
Kalymnos, is a Greek island and municipality in the southeastern Aegean Sea. It belongs to the Dodecanese and is located to the west of the peninsula of Bodrum , between the islands of Kos and Leros : the latter is linked to it through a series of islets...
was a main centre of diving for sponges. By using weights of as much as 15 kilograms (33.1 lb) to speed the descent, breath-holding
Free-diving
Freediving is any of various aquatic activities that share the practice of breath-hold underwater diving. Examples include breathhold spear fishing, freedive photography, apnea competitions and, to a degree, snorkeling...
divers would descend to depths up to 30 metres (98.4 ft) for as much as 5 minutes to collect sponges.
Free diving
Free diving includes a range of activities from simple breath-hold diving to competitive apnoea dives.Swimming underwater
The ability to dive and swim underwater can be a useful emergency skill, and is an important part of watersport and navy safety training. More generally, entering water from a height is an enjoyable leisure activity, as is underwater swimming with or without breathing apparatus.Snorkeling
The addition of a short breathing tube (snorkel) allows the diver to breathe while remaining immersed, but close to the surface.Diving with Self Contained Underwater Breathing Apparatus (SCUBA)
Scuba divers are sometimes known as frogmen, particularly divers engaged on armed forces covert operations.Open circuit
Breathing systems consist of one or more diving cylinderDiving cylinder
A diving cylinder, scuba tank or diving tank is a gas cylinder used to store and transport high pressure breathing gas as a component of a scuba set. It provides gas to the scuba diver through the demand valve of a diving regulator....
s containing breathing gas at high pressure connected to a diving regulator
Diving regulator
A diving regulator is a pressure regulator used in scuba or surface supplied diving equipment that reduces pressurized breathing gas to ambient pressure and delivers it to the diver. The gas may be air or one of a variety of specially blended breathing gases...
.
Rebreather sets
Closed-circuit breathing systems allow recycling of exhaled gases. This reduces the volume of gas used, making a rebreather lighter and more compact than an open-circuit breathing set. Rebreathers also make far fewer bubbles and less noise than open-circuit scuba; this makes them attractive to military, scientific and media divers.Surface supplied diving
The alternative to scuba is breathing gases supplied via an umbilicalUmbilical cable
An umbilical cable or umbilical is a cable which supplies required consumables to an apparatus. It is named by analogy with an umbilical cord...
from the surface, often from a diving support vessel
Diving support vessel
A diving support vessel is a ship that is used as a floating base for professional diving projects.Commercial Diving Support Vessels emerged during the 1960s and 1970s when the need arose for diving operations to be performed below and around oil production platforms and associated installations in...
but sometimes, indirectly via a diving bell
Diving bell
A diving bell is a rigid chamber used to transport divers to depth in the ocean. The most common types are the wet bell and the closed bell....
. Surface-supplied divers almost always wear diving helmet
Diving helmet
Diving helmets are worn mainly by professional divers engaged in surface supplied diving, though many models can be adapted for use with scuba equipment....
s or full face diving mask
Full face diving mask
A full-face diving mask is a type of diving mask that seals the whole of the diver's face from the water and contains a mouthpiece or demand valve that provides the diver with breathing gas...
s. An alternative to SCUBA diving, called "SNUBA
Snuba
Snuba is an underwater breathing system developed by Snuba International.The word Snuba is a portmanteau of "snorkel" and "scuba". The swimmer uses swimfins, a diving mask, weights, and diving regulator as in scuba diving....
" or "hooka" diving, has the diver supplied via an umbilical from a small cylinder or compressor on the surface. It is popular for light work such as hull cleaning, and also as a tourist activity for those who are not SCUBA-certified.
Saturation diving
Saturation diving lets professional divers live and work at depth for days or weeks at a time. This type of diving allows greater economy of work and enhanced safety. After working in the water, divers rest and live in a dry pressurized habitat on or connected to a diving support vesselDiving support vessel
A diving support vessel is a ship that is used as a floating base for professional diving projects.Commercial Diving Support Vessels emerged during the 1960s and 1970s when the need arose for diving operations to be performed below and around oil production platforms and associated installations in...
, oil platform
Oil platform
An oil platform, also referred to as an offshore platform or, somewhat incorrectly, oil rig, is a lаrge structure with facilities to drill wells, to extract and process oil and natural gas, and to temporarily store product until it can be brought to shore for refining and marketing...
or other floating work station, at the same pressure as the work depth. They may be transferred in a diving bell
Diving bell
A diving bell is a rigid chamber used to transport divers to depth in the ocean. The most common types are the wet bell and the closed bell....
. Decompression at the end of the dive may take many days.
Diving training
Underwater diving training should come from a qualified diving instructor, to be safe. This is available from many diving training bodies.Basic Dive Training entails the learning of skills required for the safe conduct of activities in an underwater environment, such as the buddy system, dive planning, and use of dive tables.
Basic underwater skills that a beginner should learn include:
- Equalization – the adjustment the Eustachian tube in the ear needs to do when submerged in the higher pressured environment underwater.
- Underwater breathing – the skill of breathing through the apparatus. All divers must get used to this way of breathing.
- Mask clearing – This is done to make sure that there will not be anything that will obstruct the diver's view as well as to remove any water that might come into the mask.
- Air sharing – the act of multiple divers sharing one air supply.
- Buoyancy – the right buoyancy allows the diver to move about underwater comfortably. Amount of equipment, buoyancy compensators, and amount of air in the lungs all come to play in maintaining buoyancy. More air in the lungs makes for more buoyancy, while less air makes for less buoyancy.
- Diving signals – diving signals may vary, but its purpose is to be able to communicate with other divers. It should be clear among a group of divers what the diving signals to be used are before the dive.
Dangers of diving
- Decompression sicknessDecompression sicknessDecompression sickness describes a condition arising from dissolved gases coming out of solution into bubbles inside the body on depressurization...
- Nitrogen narcosisNitrogen narcosisNarcosis while diving , is a reversible alteration in consciousness that occurs while scuba diving at depth. The Greek word ναρκωσις is derived from narke, "temporary decline or loss of senses and movement, numbness", a term used by Homer and Hippocrates...
- DrowningDrowningDrowning is death from asphyxia due to suffocation caused by water entering the lungs and preventing the absorption of oxygen leading to cerebral hypoxia....
- BarotraumaBarotraumaBarotrauma is physical damage to body tissues caused by a difference in pressure between an air space inside or beside the body and the surrounding fluid...
- Oxygen toxicityOxygen toxicityOxygen toxicity is a condition resulting from the harmful effects of breathing molecular oxygen at elevated partial pressures. It is also known as oxygen toxicity syndrome, oxygen intoxication, and oxygen poisoning...
- Shallow water blackoutShallow water blackoutA shallow water blackout is a loss of consciousness caused by cerebral hypoxia towards the end of a breath-hold dive in water typically shallower than five metres , when the swimmer does not necessarily experience an urgent need to breathe and has no other obvious medical condition that might have...
- Deep water blackoutDeep water blackoutA deep water blackout is a loss of consciousness caused by cerebral hypoxia on ascending from a deep freedive or breath-hold dive, typically of ten metres or more when the swimmer does not necessarily experience an urgent need to breathe and has no other obvious medical condition that might have...
- On jumping into water: divers sometimes jump into water feet first from some height above the water (e.g. from a large boat or from a pierPierA pier is a raised structure, including bridge and building supports and walkways, over water, typically supported by widely spread piles or pillars...
). Jumping into the water headfirst is unsafe for those wearing any sort of scuba or snorkelling equipment. In particular, an open-circuit scuba on the back is big and hard and heavy and during a headfirst dive into water may cause back or neck injury or break the neck.
Diving in submersibles
SubmarineSubmarine
A submarine is a watercraft capable of independent operation below the surface of the water. It differs from a submersible, which has more limited underwater capability...
s, submersible
Submersible
A submersible is a small vehicle designed to operate underwater. The term submersible is often used to differentiate from other underwater vehicles known as submarines, in that a submarine is a fully autonomous craft, capable of renewing its own power and breathing air, whereas a submersible is...
s and 'hard' diving suit
Diving suit
A diving suit is a garment or device designed to protect a diver from the underwater environment. A diving suit typically also incorporates an air-supply .-History:...
s enable undersea diving to be carried out within a dry environment at normal atmospheric pressure, albeit more remotely. Underwater robot
Robot
A robot is a mechanical or virtual intelligent agent that can perform tasks automatically or with guidance, typically by remote control. In practice a robot is usually an electro-mechanical machine that is guided by computer and electronic programming. Robots can be autonomous, semi-autonomous or...
s and remotely operated vehicle
Remotely operated vehicle
A remotely operated vehicle is a tethered underwater vehicle. They are common in deepwater industries such as offshore hydrocarbon extraction. An ROV may sometimes be called a remotely operated underwater vehicle to distinguish it from remote control vehicles operating on land or in the air. ROVs...
s and also carry out some functions of divers at greater depths and in more dangerous environments.
See also Sea Trek.
Diving by other animals
HumanHuman
Humans are the only living species in the Homo genus...
s are not the only air-breathing creatures to dive. Marine mammal
Marine mammal
Marine mammals, which include seals, whales, dolphins, and walruses, form a diverse group of 128 species that rely on the ocean for their existence. They do not represent a distinct biological grouping, but rather are unified by their reliance on the marine environment for feeding. The level of...
s such as seals
Pinniped
Pinnipeds or fin-footed mammals are a widely distributed and diverse group of semiaquatic marine mammals comprising the families Odobenidae , Otariidae , and Phocidae .-Overview: Pinnipeds are typically sleek-bodied and barrel-shaped...
, dolphin
Dolphin
Dolphins are marine mammals that are closely related to whales and porpoises. There are almost forty species of dolphin in 17 genera. They vary in size from and , up to and . They are found worldwide, mostly in the shallower seas of the continental shelves, and are carnivores, mostly eating...
s and whale
Whale
Whale is the common name for various marine mammals of the order Cetacea. The term whale sometimes refers to all cetaceans, but more often it excludes dolphins and porpoises, which belong to suborder Odontoceti . This suborder also includes the sperm whale, killer whale, pilot whale, and beluga...
s, dive to feed and catch prey under the sea as do penguin
Penguin
Penguins are a group of aquatic, flightless birds living almost exclusively in the southern hemisphere, especially in Antarctica. Highly adapted for life in the water, penguins have countershaded dark and white plumage, and their wings have become flippers...
s and many seabird
Seabird
Seabirds are birds that have adapted to life within the marine environment. While seabirds vary greatly in lifestyle, behaviour and physiology, they often exhibit striking convergent evolution, as the same environmental problems and feeding niches have resulted in similar adaptations...
s, as well as various reptile
Reptile
Reptiles are members of a class of air-breathing, ectothermic vertebrates which are characterized by laying shelled eggs , and having skin covered in scales and/or scutes. They are tetrapods, either having four limbs or being descended from four-limbed ancestors...
s: turtle
Turtle
Turtles are reptiles of the order Testudines , characterised by a special bony or cartilaginous shell developed from their ribs that acts as a shield...
s, saltwater crocodile
Saltwater Crocodile
The saltwater crocodile, also known as estuarine or Indo-Pacific crocodile, is the largest of all living reptiles...
s, seasnakes and Marine Iguana
Marine iguana
The Marine Iguana is an iguana found only on the Galápagos Islands that has the ability, unique among modern lizards, to live and forage in the sea, making it a marine reptile. The Iguana can dive over 30 ft into the water. It has spread to all the islands in the archipelago, and is...
s. Many mammals, birds and reptiles also dive in freshwater rivers and lakes.
Further reading
- Lang, Michael A., and Alf O. Brubakk, eds. The Future of Diving: 100 Years of Haldane and Beyond. Washington, D.C.: Smithsonian Institution Scholarly Press, 2009.