Before they return to the open air, professional divers heading for the surface after a deep saturation dive must spend time in a decompression chamber, where they breathe a gas mixture containing helium. The tiny molecules of helium, an extremely light gas, infiltrate into the watch. During decompression, the helium is unable to escape from the waterproof case quickly enough, creating a pressure differential that could force the crystal out of the watch case. Rolex engineers created a gas escape valve fitted with a spring: it opens when the difference in pressure between the inside and outside of the watch reaches 3 to 5 bars, allowing the helium to escape, thereby protecting the watch.

The new version of the Sea-Dweller is equipped with calibre 3235, a new-generation movement entirely developed and manufactured by Rolex. A consummate demonstration of technology, at the forefront of the art of watchmaking, this self-winding mechanical movement led to the filing of several patents and offers fundamental gains in terms of precision, power reserve, resistance to shocks and magnetic fields, convenience and reliability.

The Rolex Deepsea owes its exceptional strength, waterproofness and pressure resistance to the exclusive Ringlock system. This innovative case architecture patented by Rolex enables the watch to resist the massive pressure exerted by water at the depth of 3,900 metres (12,800 feet), equivalent to a weight of approximately 3 tonnes on the watch. Its construction is based on three elements: a nitrogen-alloyed steel central ring forms the backbone of the system, accompanied by a 5.5 mm‑thick, domed sapphire crystal and a case back in grade 5 titanium.