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 have even killed him. This caused Cousteau to have to change his plans in becoming a naval pilot, but it eventually worked out because of his passion for the ocean. In Toulon, where he was serving on the "Condorcet", Cousteau carried out his first underwater experiments, thanks to his friend Philippe Tailliez who in 1936 lent him some Fernez underwater goggles, predecessors of modern swimming goggles. Cousteau also belonged to the information service of the French Navy, and was sent on missions to Shanghai and Japan (1935–1938) and in the USSR (1939). On 12 July 1937 he married Simone Melchior,