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
The Silent World: A Story of Undersea Discovery and Adventure and 16 pages of color photos, made available by "National Geographic Magazine". The hand-held work in Ektachrome "is the first ever made in significant depths, using artificial light and scientific color correction." 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,