Rolex Sea-Dweller
A diving watch for saturation divers, with a valve that lets helium out of the case.
Saturation divers live in pressure chambers for days, and the helium in their breathing gas gets into watches and can blow off the crystal when the pressure is lowered. With Comex, Rolex developed a valve that lets the gas out. The Sea-Dweller could go much deeper than the Submariner.
Materials: Stainless steel, thick crystal; self-winding movement
Manufacture: Made in Geneva; developed with the diving company Comex.
The helium valve on the side of the case.
The thicker case and the rotating bezel.