Rolex Submariner Sea-DwellerIn 1926, Rolex’ visionary founder Hans Wildorf patented the world’s first waterproof and dustproof watch case: the famous ‘Oyster.’ Three decades later, in 1953, Rolex introduced one of the world’s first wristwatches geared specifically towards divers: the Submariner. Rolex had to confront a number of challenges when designing its first dive watch. The watch obviously had to withstand significant amounts of pressure and had to accurately measure time spent underwater, which the first Submariner achieved by introducing a 330ft/100m depth rating and a rotating diving bezel. It also had to be easily legible in conditions of reduced visibility yet aesthetically pleasing. Hence, the Sub’s iconic large white tritium hour markers and Mercedes hands set against a contrasting black dial.During the 1960s, the needs of professional divers working at great depths led to the development of the first ‘ultra water resistant’ tool watches designed for conducting safe diving operations at depths of 300 meters (1,000 ft.). However, these were still not sufficient for deep-sea divers who experienced failure as their watch crystals broke during compression due to the build-up of helium. To aid these divers, Rolex released in 1967 the Sea-Dweller Submariner (ref. 1665) in cooperation with the French engineering and deep-sea diving company COMEX. The Sea-Dweller range has been standard issue for COMEX divers and since 1977 Rolex has even produced them with customized COMEX dials.By increasing the thickness of the crystal and incorporating a helium escape valve for saturation diving, the early Sea-Dweller could be taken as deep as 610 meters (2,000 ft). A characteristic aspect of the Sea-Dweller is the absence of the date magnifier (‘cyclops’) that is present on other Rolex Oyster models with a date complication.REF.1665Double Red Sea-DwellerThe first Sea-Dweller reference (1665) was launched in 1967. During the first 10 years of production, the two lines of text “Sea-Dweller Submariner 2000” on the dial were printed in red, earning it the nickname ‘Double-Red Sea-Dweller’ or DRSD. From 1977 until the end end of the 1665’s production run in 1983 the text was printed in white instead.