The Mark V diving helmet, introduced by the U.S. Navy in 1916 and used extensively through World War II, is an iconic piece of deep-sea diving equipment. This particular example showcases the classic heavy bronze and copper construction, designed to withstand the rigors of deep-water operations. With its four reinforced glass viewing ports, protective grills, and air intake/exhaust valves, the Mark V was engineered for both safety and efficiency in demanding underwater conditions. The patina, repair, and overall wear on this helmet suggest significant use, adding to its historical appeal. These helmets were integral to salvage operations, underwater demolitions, and repair missions, making them a prized collectible among military and diving enthusiasts today.