Before the many innovations of Cousteau, if anyone wanted to dive underwater, it would be quite tedious. The diving suits were bulky, heavy, and expensive. But thanks to the aqualung (or SCUBA lung), decompression chambers that go more than 300 feet, undersea cameras, rubber scuba suit, underwater research facilities, and just the act of scuba diving itself, we have a better understanding of marine life, and how to coexist with it, and protect it. In the early 1940s, he started building the prototypes for his infamous aqualung, and began testing in 1942. At the time it was very rudimentary, but he would keep fixing and revising it for the rest of his life. In the video below, you will see a short clip of him and some of his men testing the aqualung for the first time on the French- Mediterranean coast.