Émile Gagnan was a French engineer born on April 12, 1901. He is best known for co-inventing the modern scuba diving regulator, which allows divers to breathe underwater. Gagnan developed this device in collaboration with Jacques Cousteau, a famous explorer and filmmaker, in the early 1940s. Their invention revolutionized underwater exploration and recreational diving. Gagnan's work extended beyond diving technology; he also contributed to various engineering projects throughout his career. His innovations have had a lasting impact on both the diving industry and marine research, making underwater environments more accessible to scientists and enthusiasts alike.