The Rolex Oyster Perpetual Date Sea-Dweller is a line of divers watches manufactured by Rolex, with an underwater diving depth rating from 1,220 meters (4 000 ft) up to 3,900 metres (12,800 ft) for the Sea-Dweller Deepsea model. Launched in 1967 with a diving depth of 610 metres (2 000 ft), the Sea-Dweller features a gas escape valve, developed by the brand specifically for watches. It allows the helium trapped in the watch while under water to be released at a certain pressure during decompression, while keeping the watch case waterproof. The current Sea-Dweller models are available in steel or steel and yellow gold, and have a 43 mm case.
The Deepsea model comes in a 44 mm case in steel and is equipped with the brand's patented Ringlock system, which was designed to provide a higher degree of pressure resistance.
The Rolex Oyster Perpetual Sea-Dweller Submariner 2000 (1665) was originally developed in 1967 but it wasn’t until 1971 that it became available to the public.. The delay was probably due to issues with obtaining the patent for the helium escape valve. The Rolex helium valve was the brainchild of Robert A. Barth, a US Navy diver who pioneered saturation diving during the US Navy Genesis and SEALAB missions led by Dr. George F. Bond. In the past, it was wrongly assumed the Sea-Dweller was developed in cooperation with Comex S.A. industrial deep-sea diving but the French company became a partner of Rolex only in late 1971. The first version of the Sea-Dweller was the so-called "Single Red" with a depth rating of 500 metres (1,600 ft). Most of these watches were awarded to pioneers in underwater exploration like Robert Palmer Bradley, who was a pilot of Deepstar 4000. Later versions had an increased depth rating of 610 metres (2,000 ft).
Most Sea-Dweller watches incorporate a helium escape valve for saturation diving. Early Sea-Dweller models, however, did not always have the valve. Until the 2017 introduction of the r126600 model, Sea-Dweller's were also distinguished by the absence of the date magnifier ("cyclops") present on most other Rolex models as it was impossible to attach a cyclops with Ultraviolet (UV) light curing adhesive at the top of a watch crystal exposed to the pressure encountered at its test depth. The Sea-Dweller diving watch range has been standard issue for Comex divers since 1977.
The Sea-Dweller Submariner 2000 watches have two red text lines on the watch dial, which led to an unofficial "Double Red" designation by watch collectors. The Rolex Sea-Dweller 2000 watch case has a diameter of 40.0 mm (1.57 in) mm and a thickness of 14.7 mm (0.58 in).
The Sea-Dweller Submariner 2000 models were succeeded by the Rolex Oyster Perpetual Sea-Dweller 4000 (4000 ft = 1220 m) model, with an increased depth rating of up to 1,220 metres (4,000 ft). The last Comex Sea-Dweller 4000 Rolex reference number is 16600. This watch has been issued to Comex divers since 1992. The Rolex Sea-Dweller 4000 watch case has a diameter of 40.0 mm (1.57 in) mm and a thickness of 15.5 mm (0.61 in) (crystal thickness 4 mm (0.16 in)), and case and bracelet weight of 165 g (5.8 oz). The watch was discontinued in 2008.
In 2014 Rolex re-introduced the Sea-Dweller with a new 116600 reference. This watch retained the historic 40mm case size but was updated with a cerachrom case.