In 1953, Rolex successfully tested a prototype watch called the Deep Sea Special strapped outside the bathyscape FNRS-2 to a depth of 3,150m or 10,336ft. Rolex proved its design mantra with an ultra-rigid Oyster case. By Basel 1954, they 
had raised the depth rating on all Submariners to 180m or 600ft, in conjunction with the release of the Submariner model 6204. On January 23, 1960, Rolex pushed the envelope further with the Rolex Piccard (model 7205) attached to the bathyscape Trieste that successfully dived to a depth of 10,916m or 35,800ft. The submariner made a great reputation in professional diving circles that in 1967; Rolex released its first Sea Dweller (model 1665) with the collaboration of COMEX (a French professional deep sea diving company). Fast-forward forty years to Basel in 2008; Rolex has once again forged a technological breakthrough in the mould of their latest divers watch the Sea-Dweller DEEPSEA (SDDS). The SDDS has a large 43mm diameter care and has a thickness of 18mm. No Rolex before it has been larger or thicker. Ultimately this is the most imposing Rolex to date. According to Rolex, “The new Oyster Perpetual Sea-Dweller DEEPSEA is a product of man’s inherent desire to push the boundaries of his dreams and his potential”.
Apart from the size, the first thing you will notice on the new SDDS is the ultra smooth bezel. It contains the new CERACHROM disc, which is primarily made of ceramic. The numerals and graduations are platinum filled then applied with PVD coating, a technique patented by Rolex. The triangle marker on the CERACHROM disc is illuminated using a capsule filled luminescent compound developed by Rolex that emits a blue glow. Similar in appearance to its predecessor, the indices on the dial features white gold surrounds now slightly larger to increase legibility, partially coated with a new luminescent material that also emitted a blue glow. Everything on the dial is larger, from the hour and minute hands to the numerous inscriptions on the dial. The chapter ring shows “RING LOCK SYSTEM” and “ORIGINAL GAS ESCAPE VALVE”. The Ring Lock System features a new case architecture developed and patented by Rolex. It uses a high performance nitrogen-alloyed stainless steel ring that can withstand the extreme pressures exerted by the ultra-thick synthetic sapphire crystal and the case back. Both the crystal and the titanium alloy case back are domed to enable it to seal the watch shut-tight the greater the pressure/depth. Something common with the superseded Sea-Dweller is the Gas Escape Valve. Essential for serious deep-sea divers during resurface to allow minute gases to escape the watchcase thus avoiding damaging the crystal/watch. Functional designs like the non-cyclops date window to the triplock crown are carried over. At least engineers from Rolex still follow the proven rule “if it isn’t broke, don’t fix it”.
Often overlooked on a Rolex watch is the movement. It is probably irrelevant for many, as Rolex have been making robust timepieces that stay precise and reliable for decades with minimal service. Another surefire movement found inside the SDDS is the Rolex caliber 3135. It uses the revolutionary blue Parachrom hairspring that was co-developed by Rolex and the Swiss University. This special alloy is virtually nonmagnetic (hence it resists timing deviations even around high magnetic fields) and is highly resistant to shocks. The Parachrom hairspring was tested by Rolex and was deemed 10 times more shock resistant than ordinary hairsprings. In usual high Rolex standards, each movement are COSC certified and has a power reserve of 48 hours.
One of the SDDS technological highlights is its certified depth rating of 3,900m or 12,800ft. At 12,800ft, it is equivalent to 2.98 metric tons of water pressure exerted on its case. It would seem 300m is more than enough for any dive watch, but for what it’s worth, Rolex is trying to push the boundaries and applying 
in-house developed high technology to its watches. The massive depth rating on the SDDS is similar to the highest attainable speed in a car. You won’t really drive it to its maximum, but its good to know the technology is there. It is a challenge to Rolex’s engineers to release the best divers watch available and to continue the brand’s status of being the king of divers watches. Rolex states “this new-generation diver’s watch confirms the supremacy of Rolex in the mastery of waterproofness and demonstrates an ever-present pursuit of excellence”. With the technology involved with every SDDS, exclusive testing equipment had to be developed with the help of COMEX (Compagnie Maritime d’Expertise) as each SDDS must pass rigorous waterproof ness tests. Another huge improvement over its predecessor is the beefier bracelet and the new Glidelock clasp. The bracelet feels more robust and the new Glidelock clasp offers a double extension system. It easily adjusts to newer thicker diving suits whilst at the same time allows for very fine adjustments without requiring any tools. The clasp can be adjusted up to a length of 18mm, in 1.8mm increments.
Adjustments can also be made without the need to remove the watch while worn on the wrist. With this clasp, gone are the days of half links and trips to watch dealers to adjust a loose or a tight bracelet. Another great design principle is the use of brushed center bracelet links, an essential requirement for every hardwearing divers tool watch.
The Rolex Sea-Dweller DEEPSEA has once again conquered the deep-end in terms of mechanical divers watches. Only a few years ago, many thought that Rolex had gone sleeping on its own laurels. Lo and behold the king has once again regained his throne. Since the release of the Submariner more than fifty years ago, it has taken a great deal over twenty years to realize its greatness. With the SDDS, we may only need a couple. It is a superb piece of engineering coupled with precise timing much like its predecessor. It is a modern interpretation with virtually the same DNA as any other Submariner/Sea-Dweller. It is practical and very user-friendly for its intended purpose. This is one reason how the brand has achieved an enviable reputation. One can only expect all superseded Sea-Dwellers to increase in value over time much like all superseded submariners in the past. So what’s the verdict? Figuratively speaking, the SDDS is a Bugatti Veyron. You may never drive it to 400km/h but its good to know it is capable of doing so. Rolex has created a new König of the deep sea.