Buddy diving just before and after the Second World War. After the invention of the "aqualung" by Cousteau and Gagnan, the first commercially underwater breathing apparatus became available for sale for sporting purposes in the late 1940s. As the new sport of scuba diving rapidly expanded through the 1950s, several sporting organisations—notably the YMCA—began programmes to train swimming enthusiasts in this new aquatic pastime, and began to codify what they believed were proper practises for this expanding sport. The YMCA considered the buddy system a useful corollary to the "never swim alone" rule of their swimming and lifesaving programmes. Cousteau himself independently
Jacques Cousteau Naval College). In 1943, they made the film "Épaves" ("Shipwrecks"), in which they used two of the very first Aqua-Lung prototypes. These prototypes were made in Boulogne-Billancourt by the Air Liquide company, following instructions from Cousteau and Émile Gagnan. When making "Épaves", Cousteau could not find the necessary blank reels of movie film, but had to buy hundreds of small still camera film reels the same width, intended for a make of child's camera, and cemented them together to make long reels. Having kept bonds with the English speakers (he spent part of his childhood in the United States and