Ulysse Nardin has introduced a new skeletonized timepiece that it says is the world’s lightest mechanical dive watch. It is appropriately called the “Diver [AIR]” because only 20% of the watch movement consists of material. The rest is “air,” the Swiss watch brand said.
The watch was unveiled Tuesday at the 2025 watches and Wonders watch fair, being held till April 7 in Geneva, Switzerland.
There are few skeletonized dive watches, particularly professional quality ones with a water resistance of 200 meters. Creating such a high horology sports watch required a new skeletonized movement, the use of ultra-light and strong high-tech materials, innovative materials engineering and a modular design. The result is a dive watch that weighs a mere 52 grams with a strap and 46 grams without it.
To do this Ulysse Nardin developed a new caliber, the UN-374, and removed as much of the excess material as possible while maintaining its structural integrity. This was done by using the slender bridges to form triangles, a rigid shape found in engineering and architecture to resist bending and warping. Because of this the highly skeletonized caliber UN-374 can withstand an impact of 5,000 grams. It has been tested for general knocks and vibrations, cycling thousands of shocks over several days in the lab and in the real world, the company said.
The bridges are barely a few millimeters wide, hollowed out to save even more weight, while the winding rotor has been minimized to the essentials. The mainspring barrel was reconfigured into a flying arrangement to reduce the mass of the top bridge. Material was stripped from the barrel to lighten it further, bringing the total weight of the caliber down to just 7 grams, less than half the weight of the already lightweight UN-372 movement for the Ulysse Nardin Diver Skeleton X introduced in 2021.
The automatic winding mechanism for the Diver [AIR] remains to adhere to official standards that a dive watch must meet, with automatic winding being one of the criteria. Ulysse Nardin credits its innovative flying barrel for the movement’s impressive 90-hour power reserve.
The movement is made of light-weight titanium, which is 45% stronger than steel but difficult to manipulate. It also tends to catch fire during machining, requiring careful and slow processing, which is why it is so rarely used in watch movements, Ulysse Nardin said. It’s the first time Ulysse Nardin chose titanium for a movement.
The movement is housed in a 44mm case made of several materials led by titanium and carbon fiber (another strong and lightweight material) using a modular construction method for visual appeal and to take advantage of the low density of carbon fiber while specifying titanium to make the watch water resistant to 200 meters.
The middle case is made of 90% recycled titanium acquired through a company called, TiFast, which recovered the material from the Swiss biomedical industry, recycling it in Tuscany. Another company, Thyssenkrupp, then processed the recycled titanium to enhance its machining and deformation characteristics.
The side parts of the case are made from Nylo-Foil, a registered product made of 60% Nylo (a proprietary foil made of nylon) and 40% carbon fiber, making it even lighter than traditional carbon fiber, Ulysse Nardin explained. The Nylo is recycled from ocean netting, supplied by Fil & Fab, a French recycling start-up. The carbon fiber is recovered from some of the world’s fastest monohull sailing yachts manufactured by CDK Technologies and is recycled back into its original fibrous state by company called Extracthive. Both the Nylo and the carbon fiber are then processed by Lavoisier Composites to create the high-tech material known as Nylo-Foil.
The luminous bezel insert is forged from CarbonFoil. The escapement plays its part in this innovative approach, as it is produced from an upcycled silicon wafer supplied by company called Sigatec.
The Ulysse Nardin Diver [Air] is completed with two interchangeable ultralight, elastic straps in white and orange.