Rolex Submariner Sea-DwellerVisionary Hans Wildorf set out to make the world’s first waterproof and dust proof wristwatch and so in 1926 the ‘Oyster case’ was created. Then later on in 1953, the Rolex Submariner was born, with a water depth rating of 330ft/100M making it one of the world’s first wristwatches designed for the upcoming sport of scuba diving. The wristwatch was created for divers who needed a precise watch which could scale to such depths and be a reliable and accurate way of measuring (with the turning bezel) the time spent underwater. A major aspect of creating such a time piece was to make it easily legible yet aesthetically pleasing, hence the large contrasting white tritium hour markers and Mercedes hand on the 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 300 m (1,000 ft) depths.The Rolex Oyster Perpetual Sea-Dweller Submariner 2000 that became available in 1967 was developed from the Submariner for the Comex S.A. (industrial deep-sea diving company). By increasing crystal thickness and was produced in several variations. It had a depth rating of 610 metres (2,000 ft) and its Rolex reference number was 1665, powered by calibre 1575.Most Sea-Dweller watches incorporate a helium escape valve for saturation diving. (Early Sea-Dwellers did not always have the helium escape valve.) The model is also distinguished by the absence of the date magnifier (‘cyclops’) present on most other Rolex models.