Titanium isn’t a thing a Rolex. For the most part, the brand from Geneva leaves ceramic, titanium, and steel-titanium hybrids to its sister brand, Tudor. But the Rolex Deepsea Sea Dweller is an exception to Rolex corporate orthodoxy, and it’s the one place where watch collectors can find verifiable titanium on a Rolex watch. This offbeat choice leads the line of reasons why the Rolex Deepsea is the most compelling dive watch at the world’s best-known watch brand.

While the 1967 Sea-Dweller technically is the earliest model line ancestor of the Deepsea, the monster 116660’s – and later 126660’s – true predecessor was the mammoth Rolex Deepsea Special built in a few dozen copies from the 1950s through 1960s. That watch, which ultimately survived an external ride on a bathyscaphe to the bottom of the Mariana Trench, barely qualified as a production model. In 2012, a successor timepiece, the Deepsea Challenge, rode outside James Cameron’s personal submersible during a dive to the bottom of the world-record-depth Challenger Deep. Again, the watch was a technology testbed, not a production model.

The Deepsea Sea-Dweller is the most extreme Rolex dive watch ever offered to the public.

Opinions were mixed regarding the 2008 Rolex Deepsea Sea-Dweller. Its 44mm case was very much au courant in 2008, but the end of Rolex Sea-Dweller 16600 production earned the Deepsea a reputation as the watch that killed the much-loved “Sea-Dweller 40.” This was baseless and unfortunate. In an era of posers, the Rolex Deepsea was a good-faith effort to offer maximum substance in a watch built to a specification beyond the scope of even the most ambitious recreational divers.

To be fair, the original Deepsea is not an “everyday watch” for all wrist sizes. A thickness of nearly 18mm does more than the case diameter to constrain the prospective audience for such a machine. Its wingspan of 55.6mm between solid end links is close to IWC Big Pilot-scale. But as a party watch and a weekender, the Rolex Deepsea excels. Fans of Hollywood heroics gained an optional flourish in late 2014 with the arrival of the blue-gradient “D-Blue” dial inspired by James Cameron’s descent from the surface. This model spurred acceptance and sales never realized by the original Deepsea.

Overnight, Rolex’s “party-only” watch had become the life of the party.

Want bragging rights? Owning the ultimate Rolex dive watch will grant you a royal flush. The 3,900-meter water resistance is enabled by a cylindrical “Ring Lock” case-within-a-case that starts with a 5.5mm-thick sapphire crystal, continues with a titanium clamping ring, centers on a nitrogen-treated steel cylinder, and ends with the titanium caseback. There’s more to it, but this self-supporting pillar of strength stands at the core of every Deepsea. A side benefit to the nearly 6mm crystal is that the often awkward “Cyclops Eye” date magnifier is banished.

Each Deepsea is tested to 125% of the rated depth in COMEX-designed pressure vessels before shipping to dealers. No Rolex Submariner ever has survived a trip to 4,875 meters. The Sea-Dweller line’s signature helium escape valve is present and correct for saturation divers and ready to serve as the ultimate talking point for the rest of us.

Not every feature and flourish of the latter day “triple-six” is academic or esoteric. Rolex’s finest diving clasp arrives as standard on every Deepsea. The deployant clasp of a Submariner includes the Rolex “Glidelock” system; it includes 20mm of incremental sizing flexibility. The Sea-Dweller 116600 and 126600 feature Glidelock AND Fliplock, an additional feature that works like a traditional fold-out dive extension. The Deepsea includes Fliplock and improves on Glidelock; the sizing slider in the largest Sea-Dweller can be adjusted and fine-tuned while still on the wrist in order to avoid accidental drops over deep marine diving environments.

2018 brought a sea-change for the jumbo Sea-Dweller. A comprehensive redesign of the case, bracelet, and movement left the once unwieldy watch within a stone’s throw of ergonomic practicality. While the changes to the movement were invisible – a 48-hour power reserve became 70 – the changes to the bracelet transformed the watch for borderline wrists. What had been a 55.6mm end-link-to-end-link measurement became a more manageable 53.5mm. While that’s still sizeable, it’s an effective size that’s similar to the popular 44mm “Bettarini” case Panerai Luminor; Rolex’s audience expanded as its watch contracted.

Aesthetics received a minor nod from the Rolex design team. The 2018 watch gained a broader bracelet end link and narrower lugs. While the 2008 Deepsea often was cited as a mismatch of case width and bracelet breadth, the 2018 model revisited this balance with satisfying results.

Rolex signed its revised flagship dive watch with a new dial; the “Swiss Made” declaration at six o’clock was split for the first time by a miniature Rolex crown logo. Both the standard Deepsea and the D-Blue variant received all of the 126660 model upgrades.

Why buy a Rolex Deepsea? In short, it’s the Lamborghini Aventador of Rolex divers for used Harley Davidson money. Since 2018, an expanded pool of wrist sizes has been able to take the wheel. And in the end, one can take psychic satisfaction in owning the only Rolex watch to boast structural titanium.