Rolex Sea-Dweller
Built for saturation diving, the Sea-Dweller takes the Submariner architecture and pressurizes it to 1,220 m / 4,000 ft. The helium escape valve, the thicker case, the older red "Single Red" and "Double Red" dial variants — the Sea-Dweller is the serious tool watch in the Rolex catalog. The current 126600 (43 mm) and 126603 two-tone are the modern references.