There have been a couple of exciting record-setting moments at the fair this year. We saw Bvlgari reclaim the crown for the world’s thinnest tourbillon watch with the Octo Finissimo Ultra Tourbillon, which stands at just 1.85mm in height — case, dial, baseplate, and all. We also saw a new escapement crafted entirely in silicon, a credit belonging to Rolex, who debuted it in the all-new Land-Dweller collection. Interestingly enough, the first-ever silicon escapement in watchmaking was created by Ulysse Nardin with the Dual Direct escapement. This, however, has been discontinued permanently in favor of the Swiss lever — a story that expands here. Yet, Ulysse Nardin is not one to be short of innovations, as they’ve just claimed the title of the lightest mechanical dive watch ever made. Their latest creation, the Diver [AIR], claims to weigh a mere 52g (including the strap).

A lightweight dive watch that breaks its own record

In 2021, the Ulysse Nardin Diver X Skeleton (a controversial creation that boldly combined skeletonization with the robust requirements of a dive watch, largely due to its legibility) weighed 105.8g, reportedly 15g less than a standard robust dive watch. Today, the Diver [AIR] has managed to lose an additional 53.8g, cutting the weight by more than half compared to the Skeleton. 

While dive watches have been around since the 1950s, the first waterproof instrument from Ulysse Nardin appeared in 1893, followed by their first dive watch in 1964. In 2001, they created the Aqua Perpetual, the first and only water-resistant dive watch featuring a perpetual calendar that could function at depths of 200m.

Evidently, creating the world’s lightest mechanical dive watch wasn’t simply about removing material. It required a complete reimagining of the watch’s core architecture.

Building on the UN-372 movement from the Diver X Skeleton, Ulysse Nardin’s engineers developed the innovative UN-374 caliber. This new movement was completely redesigned with one counterintuitive principle in mind: removing material to make the structure stronger.

This paradoxical result was achieved by configuring the slender bridges into triangular formations, a shape renowned in engineering and architecture for its resistance to bending and warping. The bridges are barely a few millimeters wide and hollowed out to reduce weight further. The winding rotor has been pared down to only the essential components. Even the mainspring barre has been reimagined as a “flying” arrangement to eliminate the weight of the top bridge.

These modifications reduced the caliber’s weight to a mere 7g, yet it houses a hefty power reserve of up to 90 hours. And despite the watch being 80% air and only 20% material, the highly skeletonized caliber is able to withstand an impact of 5,000g — and that’s g for force of gravity, in case you were wondering how much it can survive underwater. 

Ulysse Nardin ventured into material science

Creating such a lightweight timepiece required Ulysse Nardin to look beyond traditional watchmaking materials. Titanium was selected for the movement (a first for the brand), in addition to a silicon escapement that’s produced from an upcycled silicon wafer supplied by Sigatec. Speaking of which, Ulysse Nardin’s approach was to partner up with industry leaders and startups to integrate innovative, recycled components. Other components include:

For the 44mm case, Ulysse Nardin developed a modular construction using titanium and carbon fiber. The latter material, with its incredibly low density (1.8g/cm³), provides significant weight savings while maintaining visual appeal. Since carbon fiber isn’t inherently waterproof, the movement is housed in a titanium middle case, ensuring water resistance to 200m.

Tech Specs: Ulysse Nardin Diver [AIR]

Reference: Ref. 3743-170-2A/0A
Movement: Self-winding UN-374 Manufacture calibre; 90-hour power reserve
Functions: Hours and minutes; central seconds
Case: 44mm × 14.7mm; 90% recycled titanium (middle case and case back), Nylo®-Foil (side parts), CarbonFoil (concave rotating bezel); water-resistant to 200m
Dial: Skeletonized
Strap: Orange elastic fabric strap; additional white elastic fabric strap
Price: CHF 36,000 (incl. VAT) / USD 38,000 (excl. VAT) / €38’400  (incl VAT) / GNP 33,420 (incl. VAT)