WThe history of scuba diving is closely linked with the history of scuba equipment. By the turn of the twentieth century, two basic architectures for underwater breathing apparatus had been pioneered; open-circuit surface supplied equipment where the diver's exhaled gas is vented directly into the water, and closed-circuit breathing apparatus where the diver's carbon dioxide is filtered from the exhaled breathing gas, which is then recirculated, and more gas added to replenish the oxygen content. Closed circuit equipment was more easily adapted to scuba in the absence of reliable, portable, and economical high pressure gas storage vessels. By the mid-twentieth century, high pressure cylinders were available and two systems for scuba had emerged: open-circuit scuba where the diver's exhaled breath is vented directly into the water, and closed-circuit scuba where the carbon dioxide is removed from the diver's exhaled breath which has oxygen added and is recirculated. Oxygen rebreathers are severely depth limited due to oxygen toxicity risk, which increases with depth, and the available systems for mixed gas rebreathers were fairly bulky and designed for use with diving helmets. The first commercially practical scuba rebreather was designed and built by the diving engineer Henry Fleuss in 1878, while working for Siebe Gorman in London. His self contained breathing apparatus consisted of a rubber mask connected to a breathing bag, with an estimated 50–60% oxygen supplied from a copper tank and carbon dioxide scrubbed by passing it through a bundle of rope yarn soaked in a solution of caustic potash. During the 1930s and all through World War II, the British, Italians and Germans developed and extensively used oxygen rebreathers to equip the first frogmen. In the U.S. Major Christian J. Lambertsen invented a free-swimming oxygen rebreather. In 1952 he patented a modification of his apparatus, this time named SCUBA, an acronym for "self-contained underwater breathing apparatus," which became the generic English word for autonomous breathing equipment for diving, and later for the activity using the equipment. After World War II, military frogmen continued to use rebreathers since they do not make bubbles which would give away the presence of the divers. The high percentage of oxygen used by these early rebreather systems limited the depth at which they could be used due to the risk of convulsions caused by acute oxygen toxicity.
WEduard Admetlla i Lázaro was a Spanish scuba diving pioneer, underwater cameraman and photographer, designer of underwater camera housings, designer of a self-contained underwater breathing apparatus (scuba), tester of scuba diving gear for the Nemrod trade mark, writer, director of TV series, explorer and broadcaster.
WJacques-Yves Cousteau, was a French naval officer, explorer, conservationist, filmmaker, innovator, scientist, photographer, author and researcher who studied the sea and all forms of life in water. He co-developed the Aqua-Lung, pioneered marine conservation and was a member of the Académie Française.
WHans Hass was an Austrian biologist and underwater diving pioneer. He was known mainly for being among the first scientists to popularise coral reefs, stingrays and sharks. He pioneered the making of documentaries filmed underwater and led the development of a type of rebreather. He is also known for his energon theory and his commitment to protecting the environment.
WPhilippe Tailliez was a friend and colleague of Jacques Cousteau. He was an underwater pioneer, who had been diving since the 1930s.
WMajor Teseo Tesei was an Italian naval officer, who invented the human torpedo used by the Regia Marina during World War II.
WVintage scuba is scuba equipment dating from 1975 and earlier, and the practice of diving using such equipment.