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
Christian J. Lambertsen Breathing Apparatus). Although diving regulator technology was invented by Émile Gagnan and Jacques-Yves Cousteau in 1943 and wasn't originally related to rebreathers, the current use of the word SCUBA is largely attributed to Gagnan's and Cousteau's invention. The US Navy considers Lambertsen to be "the father of the Frogmen". Lambertsen was born in Westfield, New Jersey and attended Rutgers University in New Brunswick, New Jersey, graduating in 1939 with a bachelor of science degree. He graduated from medical school at University of Pennsylvania, Philadelphia, Pennsylvania in 1943. Lambertsen was awarded Honorary Doctor of Science Degree from Northwestern University in 1977.