Rolex Sea-Dweller

Rolex created the Sea-Dweller in 1967 for divers working out of pressurised habitats, and improved it afterwards in partnership with Comex. The defining part is not the depth figure but the helium escape valve in the case side, which opens by itself when helium that seeped in during a saturation dive builds up inside the case on the way back to the surface. The 43 mm Sea-Dweller is rated to 1,220 m, runs a unidirectional bezel with a black Cerachrom insert and an Oysterlock clasp with the Glidelock extension, and was the first in the line to take a cyclops over the date; it is made in Oystersteel and in Oystersteel with yellow gold. Rolex now lists the Deepsea as a family of its own, the 44 mm model rated to 3,900 m and built on the Ringlock System case architecture.