Solo diving II. In the late 1940s, after the invention of the Aqua-lung by Cousteau and Gagnan, the first retail underwater breathing apparatus for sport was commercially marketed. As the sport expanded through the 1950s, several sporting organisations – notably the Young Men's Christian Association (YMCA) – began scuba training programmes for swimming enthusiasts, thus began the codification of what was believed to be proper practices for the expanding amateur sport of scuba diving. The buddy system was thought to be a useful corollary to the "never swim alone" edicts of the YMCA swimming and lifesaving programmes. Cousteau independently implemented a buddy
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