right|thumb|Recreational scuba diver

thumb|The undersea [[kelp forest of Anacapa Island off of the coast of Oxnard, California]]

right|thumb|Diver looking at a [[shipwreck in the Caribbean Sea]]

Scuba diving is an underwater diving mode where divers use breathing equipment completely independent of a surface breathing gas supply, and therefore has a limited but variable endurance. In an emergency they had to jettison their weights. In the 1960s adjustable buoyancy life jackets (ABLJ) became available, which can be used to compensate for loss of buoyancy at depth due to compression of the neoprene wetsuit and as a lifejacket that will hold an unconscious diver face-upwards at the surface, and that can be quickly inflated. The first versions were inflated from a small disposable carbon dioxide cylinder, later with a small direct coupled air cylinder, and eventually with a low-pressure feed from the regulator first-stage to an inflation/deflation valve unit with an oral inflation valve for backup. The inflation system and a dump valve lets the volume of the ABLJ be controlled as a buoyancy aid. In 1971, the stabilizer jacket was introduced by ScubaPro. This class of buoyancy aid is known as a buoyancy control device or buoyancy compensator. or the dive team, do equipment checks to ensure everything is in good working order, ready for use, and correctly fitted. Recreational divers are responsible for planning their own dives, unless in training, when the instructor is responsible. It is helpful to note what equipment was used for each dive and what the conditions were like for reference when planning another similar dive. For example, the thickness and type of wetsuit used during a dive, and if it was in fresh or salt water, will influence the amount of weight needed. Knowing this information and taking note of whether the weight used was too heavy or too light can help when planning another dive in similar conditions. In order to achieve a level of certification the diver may be required to present evidence of a specified number of logged and verified dives. the CMAS Scientific Committee,

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Further reading

  • Cousteau J.Y. (1953) Le Monde du Silence, translated as The Silent World, National Geographic (2004)
  • Ellerby D. (2002) The Diving Manual, British Sub-Aqua Club (BSAC)
  • Dive Leading, BSAC
  • The Club 1953–2003, BSAC

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