The Rolex Sea-Dweller is a toolwatch which is designed for professional use underwater. Just like the submariner the Sea-Dweller has military connections. The Sea-Dweller is made to meet the technical limits of a mechanical watch, this watch is made for very extreme diving expeditions. Developed by a Military lab (US-navy SEAL) and tested by many divers. Especially for the changing pressures while diving Rolex developed the Helium valve to absorb decompression.
Macro shot from the dial of the Sea-Dweller.
The rolex (helium valve) original gas escape valve and caseback.
