The Reference 1665 Sea-Dweller evolved from the specialized dive watches Rolex had produced for the Marseille-based deep sea diving company, COMEX (Compagnie Maritime d’Expertise). A commercial version marketed to the general public, the early generation models of the Sea-Dweller could withstand pressure up to impressive depths of 2000 feet or 610 meters. All, like the present model with Mark IV dial, feature a helium escape valve and were the world’s most robust, water resistant watches of their era. Indeed, after compression dives at such depths, where they would breathe a mixture of pressurized hydrogen-helium-oxygen, the tiny helium atoms would penetrate normal dive watches and pop their crystals out during decompression. Rolex solved this problem with COMEX, inventing the helium escape valve, permitting the trapped helium to easily escape. Between 1971 and 1977, Rolex printed the words “SEA-DWELLER” and “Submariner 2000” in red on two lines on the watch’s dial, fittingly nicknamed the “double red” years later by collectors. Preserved in original, unrestored condition, the present lot most probably spent its life on dry land than reaching such unfathomable depths. A sporty and versatile watch that is both highly collectible and suitable for daily wear.