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 with American television companies (ABC, Métromédia, NBC) created the series "The Undersea World of Jacques Cousteau", with the character of the commander in the red bonnet inherited from standard diving dress intended to give the films a "personalized adventure" style. This documentary television series ran for ten years from 1966 to 1976. A second documentary series, "The Cousteau Odyssey", ran from 1977 to 1982 on public television stations. In 1970, he wrote the book "The Shark: Splendid Savage of the Sea" with his son Philippe. In this book, Cousteau described the oceanic whitetip shark as "the most dangerous of all