The Sea-Dweller, the first name of the Rolex Deepsea, was born from a specific functional need.
The COMEX Company (Compagnie Marittime d’Expertise) needed watches resistant to very deep and long diving, able to support their scuba divers engaged in the maintenance of submarine offshore drilling plants. Divers were at that age equipped with oxygen and helium blend, and used compensation rooms to get their body used to the effects of the high pressure. At that depth, helium used to damage Rolex Submarner, waterproof up to 200mt: the gas could easily penetrate within the watch case, but was not as fast in getting out. This is why a special valve was added to Rolex Deepsea in order to help the helium exit.
The first watches were especially made for COMEX, and were not available for the market. The watch was introduced to the public in 1971, with the name of Sea-Dweller, resistant to 4000 feet (1220mt).
The Deepsea has a very famous success on its history: it withstanded to a deep dive at 10.916mt under the sea level, reaching the “Challenger Deep” in the Marianas Trench together with the Trieste submersible that helped Don Walsh and Jacques Piccard explorations. This was the best test ever for the Oyster case water resistance.
A newest version of this extreme watch was launched in 2007, called Sea-Dweller Deepsea, whose maximum resistance is brought to 12.800 feet (3900mt). The higher water resistance is given by the flexible titanium back and the three-component case (Ringlock System). Aesthetic innovations were also introduced, such as a bigger case (44mm), the blue luminescence of hands and indexes and a ceramic bezel with platinum numbers.