Presented in 1967, it is notably equipped with the helium escape valve, an innovation that has played a key role in underwater research since it first accompanied a new professional diving technique: saturation diving. Initially capable of descending to 610 metres (2,000 feet), since 1978 the Oyster Perpetual Sea-Dweller has been guaranteed waterproof to a depth of 1,220 metres (4,000 feet).