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
The Silent World: A Story of Undersea Discovery and Adventure The Silent World: A Story of Undersea Discovery and Adventure The Silent World (subtitle: "A story of undersea discovery and adventure, by the first men to swim at record depths with the freedom of fish") is a 1953 book co-authored by Captain Jacques-Yves Cousteau and Frédéric Dumas, and edited by James Dugan. Although a French national, Cousteau wrote the book in English. Cousteau and Émile Gagnan designed, built, and tested the first "aqua-lung" in the summer of 1943, off the southern coast of France. In the opening chapters, Cousteau recounts the earliest days of scuba diving with his diving companions