An interlock vessel has an air-tight body having open opposing ends. A portion of the body is designed to fit into a decompression (hyperbaric) chamber, wherein a diver or a patient undergoing a decompression treatment is positioned. The opposing ends are closed by pivotally moveable doors and latching assemblies that retain the door in a closed position until the pressure inside the decompression chamber and the exterior of the chamber is equalized. Both latching assemblies are manually operated.