At Watches & Wonders 2025, Ulysse Nardin is taking the covers off the lightest ever mechanical dive watch, the Diver [Air]. Weighing only 52 grams, strap included, UN’s newest diver is unexpected and impressive in a number of ways. 

Initial thoughts

UN’s engineers have succeeded in marrying lightness with utility in the Diver Air. The case, strap, and the movement in particular, have all been developed to carry as little weight as possible — without compromising structural reliability. At 52 g with the strap, and 46 g without, the Diver Air weighs about as much as 10 sheets of A4 paper.

Impressive as it is, however, the Diver Air doesn’t really look the part, which is arguably its biggest weakness. Visually the Diver Air is almost undistinguishable from the standard Diver X Skeleton, which is a shame given that this is entirely different. The result is a missed opportunity in creating something that looks like what it is, an ultra-light performance watch. 

The movement, however, looks good in a contemporary manner, with clear sapphire jewels and a clean, industrial finish.

The seven grams UN-374 movement

At the core of this ultra-light diver lies an in-house movement engineered for both lightness and sturdiness — the UN-374, with 90% recycled titanium bridges. The UN-374 only weighs a staggering 7 g and yet can run for 90 hours on a full wind at a 3 Hz frequency.

Based off Diver X Skeleton’s UN-372, the new UN-374 was tweaked to keep its structural stability while losing as much mass as possible. The watch was even tested to withstand shock of up to 5000 G, which is impressive considering its lightness.

The movement lacks any full plates, reducing the traditional baseplate’s footprint to the bare minimum. Structural bridges, measuring a few millimetres in width, support the going train, keyless works and the automatic winding system.

Some gears appear to almost float, since the hollowed-out bridges occupy minimal space. Although thin, their titanium alloy construction guarantees a reliable structural integrity. 

The winding system is still a Magic Lever variant, a design which harkens back to the Lemania-derived UN-32 calibre of the 1990s.

The barrel was reconfigured to a more complex “flying” arrangement. Such systems don’t require an upper bridge (a very suggestive example of a flying barrel can be found in the Pratt Oval Tourbillon), which brings the weight down some more.

The regulating organ itself is advanced: the balance has a silicon frame with inertia weights and a silicon hairspring with a proprietary flat end-curve — a system which we previously covered in-depth in our Freak Saga Part III story. The escapement itself is crafted from silicon.

A modular case

The 44 mm case of the Diver Air is primarily titanium, but has a multi-piece construction. There is a titanium middle case, which ensures the 200 m water resistance of the watch, paired with carbon composite case flanks. These black components are made out of 60% Nylo and 40% carbon fibre. 

Nylo is made from recycled fishnets by Fil&Fab, a French start-up. The graded carbon-fibre diving bezel is also crafted from recycled carbon and has a marbled pattern. These up-cycled and recycled materials are notable, but the end result looks a bit uninspired on the whole and the case aesthetics don’t really impress.

Key facts and price

Ulysse Nardin Diver [Air]
Ref. 3743-170-2A/0A

Diameter: 44 mm
Height: 14.7 mm
Material: Recycled titanium and carbon composite
Crystal: Sapphire
Water resistance: 200 m

Movement: Cal. UN-374
Functions: Hours, minutes and seconds
Winding: Automatic
Frequency: 21,600 beats per hour (3 Hz)
Power reserve: 90 hours

Strap: Elastic fabric strap

Limited edition: No
Availability: At Ulysse Nardin boutiques and retailers
Price: €38,400 including 21% VAT

For more, visit Ulysse-nardin.com.