There is pretty steep competition between Rolex models when referring to the historical significance between them, however, the Sea-Dweller is undoubtedly one of the most important watches ever created. First introduced in 1967 with the reference 1665, the Sea-Dweller featured innovative patented technology that helped further human exploration to parts otherwise considered impossible to reach. In collaboration with Comex and utilized in the famed SeaLab missions, the Sea-Dweller built upon the existing Rolex Submariner platform to increase the depth rating of the watch to an impressive 2000ft. This impressive increase in possible depth was the result in bulking up of the case, but more importantly, the invention and development of the Helium Escape Valve or HEV which allowed for helium molecules to transfer in and out of the watch case without damaging the watch.

Helium gas was essential in the breathing gas mixture used during the experimental saturation diving missions at the time, however, due to helium being such a small gas particle it was able to enter watches during the missions but without a method of the gas, to escape would cause the watches catastrophically fail upon decompression. The invention of the HEV was revolutionary as it allowed the helium gas watches to "escape" during decompression, thus making the watch able to reach unheard-of depths at the time.

The Rolex ref. 16600 is the third version of the Sea-Dweller and was introduced in 1988, directly succeeding the very transitional ref. 16660 "Triple 6" model, and was replaced in 2008. The ref. 16600 boasts an incredible depth rating of 4000ft or 1220m, utilizes a sapphire crystal and a unidirectional click-spring bezel, employs the Rolex in-house cal. 3135 with quick-set date functionality, and features the improved 93160 Oyster bracelet with solids end pieces.

CASE & BRACELET

The robust case is in excellent condition and has been potentially polished once previously as the original case dimensions, finishing and chamfers remain present. The case exhibits honest signs of use, but no notable elements of damage. The bezel insert features a deep navy blue coloration with very minimal signs of use and retains its tritium pearl which matches the dial perfectly. The case back retains its original factory green Rolex sticker and the black enamel remains fully present as well. The original Rolex 93160 Oyster bracelet with 592B solid end pieces retains 11 links along with the integrated diver's extension, the links exhibit no stretch from use. The bracelet will fit up to a 7 1/2-inch wrist.

DIAL & HANDS

The glossy black dial with white gold surround markers is flawless, showing no damage or age. The tritium lume plots feature a subtle eggshell patina with no degradation present under UV light inspection. The original tritium hands match the dial perfectly and exhibit no degradation when inspected under UV light.

ACCESSORIES 

None. The watch is keeping time perfectly, backed by a 1-year warranty on accurate timekeeping.