What may seem like a few minor design changes here and there actually mean a lot of serious firsts with the new-for-2017 Rolex Oyster Perpetual Sea-Dweller 50th Anniversary model reference 126600, making this replacement of the Sea-Dweller 4000 one of the more important releases of Baselworld 2017.

First and foremost, let’s begin with the tech specs, as with this new reference 126660, the Rolex Sea-Dweller has received five major updates: first, it has grown from 40mm to 43 millimeters wide, making for a very considerable difference between the Sea-Dweller 50th Anniversary and the Submariner (which is 40mm). Second, it received a cyclops over the date, a first for a Rolex Sea-Dweller and as controversial an update as the growth in size. Third, it is now powered not by the 3135 but the updated 3235 caliber (the same as the Datejust 41 reviewed here). Fourth, it has a redesigned bracelet that is now wider and makes for a more secure fit on the wrist. Last, but not least, it pays tribute to the original Sea-Dweller of 1967.

All this, of course, seriously changes the looks of the Rolex Sea-Dweller. The larger case and bracelet make it more proportionate by matching a greater diameter case with the existing thickness – that was arguably a bit disproportionate with the 40mm width of the previous 116600. Bear in mind that the thickness (no official figure on it yet but check the wristshots to get a good idea) is necessitated by the 4,000ft/1,220m water-resistance.

While in this regard the added width makes sense, the new-found cyclops – again, new for the Rolex Sea-Dweller altogether – arguably is an even more controversial decision. The Rolex Sea-Dweller, some argued, from the get-go should have been a larger alternative to the No-Date and Date Submariner models (instead, all three watches thus far had been 40mm wide) – but the cyclops, even Rolex admits, is a less obvious and more controversial addition.

A lesser-known fact is that the original Rolex Sea-Dweller of 1967 did not have a cyclops because when Rolex added it to the plexiglass front, it caused structural weaknesses in it and ultimately caused it to shatter before reaching the desired depth rating – and so the cyclops was omitted. The Rolex Sea-Dweller all until 2017 has maintained its cyclops-free looks, making yet another reason for it to be a Submariner alternative (as, clearly, not everyone is a fan of the cyclops-look). Now, in this regard, the Rolex Sea-Dweller is more in line with all other collections, with only the Deepsea now standing out from the rest, as it still does not have a cyclops over its date aperture.

The movement, as we have noted, is the new 3235, an automatic, fully Rolex-designed and -made caliber that complies with Rolex’s -2/+2 second daily accuracy (all details here) and offers an extended 70 hours of power reserve over the previous Rolex Sea-Dweller’s 48 hours. It, hence, features Rolex’s high-capacity mainspring barrel, its Chronergy escapement with paramagnetic nickel-phosphorous pallet fork and escape wheel, Paraflex shock absorbers, Parachrom hairspring, a large balance wheel with Microstella variable inertia lugs and an operating frequency of 4Hz. It is the latest and greatest tech-fest that Rolex can offer at the moment.

The new Rolex Sea-Dweller’s 904L Oyster bracelet is fitted with an Oysterlock safety clasp, Fliplock extension system for an added 26mm of reach along with the Rolex Glidelock system for 2mm-increment fine adjustments over a distance of 20mm. Typical Rolex Sea-Dweller feats such as the black Cerachrom bezel with PVD-applied platinum numerals, flat front sapphire crystal and 1,220m of water resistance enforced by a helium escape valve inside the left side of the case (see its components below) remain present.

Available exclusively with a black dial with white gold hands and indices and Chromalight lume, the stand-out feature (if we can call it that) here is the red Sea-Dweller designation over the usual depth rating and COSC certification reminder.

Lastly, along with the red lettering and among all other novelty factors of this Rolex Sea-Dweller 126600, we should consider the name and presentation because, in this special case, that matters too. Simply called the Rolex Oyster Perpetual Sea-Dweller, Rolex actually presented it as the 50th anniversary model in their windows around their Baselworld booth.

While the model name doesn’t include that anniversary reference, it’s still an interesting development in the sense that although Rolex has naturally been perpetually changing and fine-tuning long-established collections (like the Daytona, Submariner, Sea-Dweller, Datejust, Day-Date, and more), it’s been exceedingly rare for an all-new Rolex model to decidedly pay tribute to a previous version’s design element like the new Rolex Sea-Dweller 126600 does with its red Sea-Dweller text.

Last year, when everyone was expecting a new Daytona, I don’t find it a stretch to say that many were looking forward to seeing something really quite close to the Newman Daytonas of old, or at least a perfect panda dial – and yet, Rolex has decided to tip-toe their way around that. A few years ago, the re-launch of the Pepsi-bezel GMT was also close to its predecessor but very clearly different in its colors than the original. Here, however, we are looking at a clear reference to one of the defining aesthetic elements of an early Rolex collection, making it a small change, but possibly a significant one to many Rolex fans.

Anyhow, the 43mm-wide Rolex Sea-Dweller 126600 is the new and only Rolex Sea-Dweller in town from now on, as it fully replaces the 40mm-wide Sea-Dweller 4000. It looks bold and feels heavy on the wrist, but it carries that heft in a much more balanced manner when compared to how its predecessor had done.

What truly makes it an interesting step on Rolex’s part is how the new Rolex Sea-Dweller now blends more into the Rolex dive watch range with its cyclops fitted over its date, and how it stands out with its boldly different 43mm-wide diameter. In closing, it is worth imagining what this watch would have been like without the red text and the cyclops but everything as it is now – it would have made for a long-expected update bringing on better proportions and a larger alternative to those who have been on the lookout for something larger than a Submariner but not as bold as the Deepsea.

As it stands now, however, it certainly cannot be called another safe step from Rolex – they admittedly made the controversial decision of not only considerably upping the size but also adding the cyclops, rendering this a truly new Rolex Sea-Dweller that offers more than a mere face-lift (and not just by Rolex standards). Price for the new Rolex Sea-Dweller 126600 is CHF10,800 including tax. rolex.com