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SCUBA is an acronym for Self Contained Underwater Breathing Apparatus; as with radar, the acronym has become so familiar that capitalisation is often omitted. In short, scuba diving is an underwater activity practiced with the help of equipment worn by the diver, which provides a supply of breathing gas allowing the diver to remain underwater for long periods.
There are two types of SCUBA equipment:
Alternatives to diving with SCUBA equipment are:
Equipment similar to SCUBA is also used for non-diving applications:
See also Timeline of underwater technology.
The first known use of air tanks is in Italy, 15th century: Leonardo da Vinci affirmed in his Atlantic Codex (Biblioteca Ambrosiana, Milan) that systems were used at that time to artificially breathe under water, but he did not explain them in detail due to what he described as "bad human nature", that would have taken advantage of this technique to sink ships and even commit murders. Some drawings, however, showed different kinds of snorkels and an air tank (to be carried on the breast) that presumably should have no external connections. Other drawings showed a complete immersion kit, with a plunger suit which included a sort of mask with a box for air. The project was so detailed that it included a urine collector, too.
After Leonardo's studies, and those of Halley (yes, the astronomer), in the 19th century Augustus Siebe developed standard diving dress, a sort of surface supplied diving apparatus. His studies were perfected by the Frenchman Joseph Cabirol and later, more incisively, by Benoit Rouquayrol and Auguste Denayrouze, who made the diver independent of surface air supplies by developing the first modern diving cylinder.
In 1879 Henry Fluess invented the first closed circuit breathing device using stored oxygen and adsorption of carbon dioxide by a caustic soda or rebreather for the rescue of mineworkers who were trapped by water.
In 1906 the first decompression tables ("quote decompression method") were released.
In 1915 Sir Robert Davis invented the "Submarine escape apparatus", by which a compressed oxygen bottle could be opened in water in case of need, sending air to mouth. Used air could be then expelled to a filtering "false lung" from where it is finally lost.
In 1925 Yves Le Prieur invented a better developed apparatus in 1933, working with compressed air. It could permit a 20 minute stay at 7 meters and 15 minutes at 15 metres (these data appear however to be re-checked).
In 1941, during WWII, these experimental apparatuses were used for one of the best known and most spectacular war actions: Italian "Decima Mas" (elite navy corps at the orders of commander Junio Valerio Borghese) entered at nighttime the port of Alexandria, Egypt, in immersion. They used special underwater vehicles ("maiali" = pigs) and breathing apparatus, and were able to silently attach mines on the bottom of the ships, that later were effectively sunk.
In July of 1943 the Frenchman Georges Comheines was able to reach 53 meters (~174 feet), off the coast of Marseille, with a two-bottles apparatus he had developed from Le Prieur's one. Immersion lasted 2 minutes (apparently out of decompression tables).
In the following October, Frédéric Dumas reached 62 meters (~200 feet), with the apparatus co-invented by Jacques Cousteau and Emile Gagnan and named Aqua-Lung.
In 1958 the TV series SEA HUNT, introduced SCUBA diving to the TV audience.
Movies have also popularized the sport. SCUBA diving is featured in films such as The Abyss, James Bond in Thunderball and Fantastic Voyage.
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