The Aquanaut in Numbers: Which Reference to Buy

<p>Forty millimeters. That is the figure that turned the Aquanaut from a quiet 1997 curiosity into the reference people actually chase. The original 5060 wore 36mm, modest by any standard, and the 2007 arrival of the 5167 at 40mm gave the rounded octagonal case the presence buyers wanted without tipping into showy.</p><p>The case is the argument. That soft-cornered octagon, brushed on top with polished flanks, sheds the formality of the Nautilus while keeping the family silhouette. Water resistance runs 120 meters, enough for real use, and the composite "tropical" strap moulds to the wrist and shrugs off sweat and salt in a way leather never would. The embossed grid dial, with its raised checkerboard and bold applied numerals, is the visual signature you are paying for.</p><p>Inside the steel 5167A sits the caliber 324 S C, a self-winding movement with a 21,600 beat, roughly 45 hours of reserve, and a 21-carat gold rotor. It is not a chronograph or a perpetual, just a clean date automatic finished the way this maker finishes things, visible through the sapphire back.</p><p>On the wrist the 5167 reads athletic but slim, sitting flat under a cuff at around 8.1mm thick. It suits 6.75 to 7.5-inch wrists, and the integrated strap makes it feel smaller than a 40mm bracelet watch would. The light mass means it never top-heavies on a thin wrist, one reason it works as a genuine daily rather than a weekend piece.</p><p>Which reference to want: the steel 5167A-001 with the black-toned dial is the one to hold out for. The white gold 5168G jumbo at 42mm is handsome but louder and pricier, and the Travel Time 5164 adds a dual-zone complication most owners rarely set. For a single Aquanaut that does the job the line was built for, the 5167A is the buy.</p>