Jacques-Yves Cousteau was a French naval officer, explorer, ecologist, filmmaker, and researcher who lived from 1910 to 1997. He is most famous for pioneering marine conservation and underwater exploration. Cousteau co-developed the aqua-lung, which allowed extensive underwater research and filming of sea creatures in their natural environment. Throughout his career, Cousteau authored popular books and produced award-winning films and television series documenting his ocean discoveries and advocating for environmental protection.