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Underwater diving |
Underwater diving is the practice of going underwater with or without breathing apparatus.
Recreational diving 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 and types of equipment and gases used differ between types of diving.
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It is unknown when exactly the sponge became an article of use. In ancient writings Plato and Homerus the sponge is mentioned as an object used for bathing. In Kalymnos also sponge diving had it's roots in ancient times. It can be seen as the oldest profession on the island. Diving for sponges brought social and economical development to the island where the free-diving method was used. The crew went out to sea in a small boat. They used a cilyndrical object with a glass bottom to search the ocean floor for sponges. As soon as one was found, a diver went overboard to get it. He was usually naked and carried a 15 kilogram skandalopetra with him to take him down to the bottom quickly. The diver then cut the sponge loose from the bottom and put a special net around it. Depth and bottom time depended on the divers lung capacity. They usually went down to about 98 feet (about 30 m) for 3 to 5 minutes.
Free diving includes a range of activities from simple breath-hold diving to competitive apnoea dives.
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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.
The addition of a short breathing tube (snorkel) allows the diver to breathe while remaining immersed, but close to the surface.
Scuba divers are sometimes known as frogmen, particularly divers engaged on armed forces covert operations.
Breathing systems consist of one or more diving cylinders containing breathing gas at high pressure connected to a diving regulator.
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.
The alternative to scuba is breathing gases supplied via an umbilical from the surface, often from a diving support vessel but sometimes, indirectly via a diving bell. Surface-supplied divers almost always wear diving helmets or full face diving masks.
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 vessel, oil platform or other floating work station, at the same pressure as the work depth. They may be transferred in a diving bell. Decompression at the end of the dive may take many days.
Basic Dive Training entails the learning of underwater skills and other skills requisite to the successful and safe conduct of activities in an underwater environment such as the buddy system, dive planning, and use of dive tables among others. Also, underwater diving training should come from a qualified diving instructor, to be safe.
Below are some basic underwater skills that a beginner should learn:
Diving training can be got from many diving training bodies: see Category:Diver training agency.
Submarines, submersibles and 'hard' diving suits enable undersea diving to be carried out within a dry environment at normal atmospheric pressure, albeit more remotely. Underwater robots and remotely operated vehicles and also carry out some functions of divers at greater depths and in more dangerous environments.
Humans are not the only air-breathing creatures to dive. Marine mammals such as seals, dolphins and whales, dive to feed and catch prey under the sea as do penguins and many seabirds, as well as various reptiles: turtles, saltwater crocodiles, seasnakes and Marine Iguanas. Many mammals, birds and reptiles also dive in freshwater rivers and lakes.
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