Standard diving dress, also known as hard-hat or copper hat equipment, deep sea diving suit, or heavy gear, is a type of diving suit that was formerly used for all relatively deep underwater work that required more than breath-hold duration, which included marine salvage, civil engineering, pearl shell diving and other commercial diving work, and similar naval diving applications. Standard diving dress has largely been superseded by lighter and more comfortable equipment.
Standard diving dress consists of a diving helmet made from copper and brass or bronze, clamped over a watertight gasket to a waterproofed canvas suit, an air hose from a surface-supplied manually operated pump or low pressure breathing air compressor, a diving knife, and weights to counteract buoyancy, generally on the chest, back, and shoes. Later models were equipped with a diver's telephone for voice communications with the surface. The term deep sea diving was used to distinguish diving with this equipment from shallow water diving using a shallow water helmet, which was not sealed to the suit.
