SCUBA, which stands for Self Contained Underwater Breathing Apparatus, was invented by Frenchmen Jacques-Yves Cousteau and Emile Gagnan in 1943. Creating underwater breathing devices had long fascinated inventors, and some inventions had varying degrees of success, but Cousteau and Gagnan allowed adventurers to experience the ocean like never before.
Cousteau and Gagnan converted a car regulator into a device that would automatically refresh air when the diver breathed. This kept the air pressure in a diver's lungs equal to the water pressure and made SCUBA diving safe. According to About.com, they began selling their Aqua-Lung in France and later made Aqua-Lung available in England, Canada and the United States.