This Rolex Sea-Dweller Deepsea Challenge reference 126067 is the most extreme expression of the brand's modern dive watch engineering. Its automatic caliber 3230 keeps the watch to time only, which suits a reference defined less by complication than by sheer capability, and for the collector of Rolex tool watches that single-mindedness is the point. In titanium, the case measures 50mm across and 23.5mm thick, dimensions dictated by a watch built to withstand 11000 meters of water resistance rather than adapt itself to convention. That scale gives it a place apart even within the Deepsea line, where excess is part of the brief. The black dial keeps the display as direct as the case is uncompromising. More than a larger Sea-Dweller, this is Rolex testing the outer limit of what a serially produced dive watch can be.