Bathyscaph, BATH uh skaf, is a diving craft used for deep-sea observation. It can dive more than 6 miles (10 kilometers) to explore the deepest parts of the ocean. The craft consists of a thick-walled steel sphere attached to a large hull. The sphere protects the crew and scientific equipment from crushing water pressure. The hull contains several compartments filled with gasoline. The gasoline is lighter than water and gives the craft buoyancy.