Grand Seiko’s Spring Drive UFA Ushio 300 Diver is the Best of All

You’d be forgiven if dive watches weren’t the first thing that came to mind when thinking of Grand Seiko. The Japanese brand makes some of the most beautiful (if not the best) dress watches in the world, so the idea that they would hold up well to being tested underwater might seem a bit far-fetched.

Anyway, the watchmaker has had a variety in its catalog since 2008, but it was with its Evolution 9 models starting in 2022 that we could see what Grand Seiko was capable of. With the introduction of Spring Drive UFA (Ultra Fine Accuracy) last year, the Evolution 9 divers are also being updated, but not just mechanically. These watches are very wearable as well.

Long time coming

For a brand that first emerged in the 1960s and spent the first few decades developing a dress watch, diving has never been in Grand Seiko’s DNA the way it was for its predecessor Seiko, whose 62MAS from 1965 is essentially the grandfather of Japanese dive watches.

While Grand Seiko’s early Spring Drive divers were impressive, they measured a hulking 44.2mm by 14mm. Successive iterations in the 2010s and 2020s pushed the water resistance up to 600m in some cases, but didn’t really expose the measurement problem. The 2022 Ushio Divers (SLGA015 and SLGA023) brought the Evolution 9 design language to the underwater lineup, but at 43.8mm by 13.8mm with a water resistance of only 200 meters, they were far from the most functional dive watches on the market, let alone the most capable.

All that changes with the Spring Drive UFA Ushio 300 Diver.

Finding the Right Size

Fans rejoice as the new SLGB023 and SLGB025 watches come in at just 40.8mm in width and 12.9mm in thickness, yet offer the wearer a solid 300m of water resistance. In context, the measurements are basically the same measurements as the Rolex Submariner Date. The case and bracelet are both made of Grand Seiko High-Intensity Titanium, which is about 30% lighter than stainless steel without sacrificing any scratch resistance.

To increase water resistance, the crown folds down and recedes slightly behind the side guards. Meanwhile, the non-linear bezel works with 120 clicks of ceramic.

The bracelet itself has been newly designed with a three-link construction and locking extension that closes 6mm for small adjustments in three steps, and an additional 18mm for diving suit use. We personally like the GS logo on the clasp, which acts as a lock.

Call Speech

It’s not a Grand Seiko watch without a beautiful dial, and the new diver follows suit. The Ushio dial pattern, a wave-textured motif that has been part of the Evolution 9 diver lineup since 2022, returns here in gradient blue (SLGB023) and gradient green (SLGB025). Blue darkens in the deep ocean at the edges, while green refers to shallow coastal waters. The medium color gradient creates a strong contrast with the hand-drawn references.

Speaking of the indices, they have upgraded to the prominent rectangular markers of the Evolution 9 Style with diamond-cut edges and Lumibrite filling. This replaces the round hour markers that looked a little soft on previous GS divers and looks more cohesive all around.

Instead of a date window, a power-setting indicator, a longtime Grand Seiko signature, enters the face of the dial here as the caseback is solid on this reference. Not everyone will like this surfer, but it’s definitely on brand for them.

Impressive Movement

Caliber 9RB1 is a variant of the UFA movement that debuted last year in the SLGB001 and SLGB003. A 30mm x 4.7mm Spring Drive with a 72-hour power reserve and holding the distinction of being the most powerful wristwatch movement available today. That average of ±20 seconds per year (about ±3 seconds per month) is achieved by clocking a three-month-old quartz crystal oscillator vacuum-crystal oscillator with an IC, then plotting the oscillator’s frequency data across multiple temperatures for accurate thermo-compensation. It is hand-assembled at Grand Seiko’s Shinshu Watch Studio in Nagano Prefecture, and features a control switch to adjust accuracy during servicing. There is simply nothing else like it.

Specification Sheet

Pricing and Availability

The Grand Seiko Spring Drive UFA Ushio 300 Diver is priced at $12,400 for both references and hits Grand Seiko stores and select retail partners in June. The blue SLGB023 will also be available at authorized retailers, while the green SLGB025 is available at supermarkets and official stores only.

Grand Seiko Spring Drive UFA Ushio 300 Diver

Grand Seiko’s new Ushio 300 Diver is the brand’s best dive watch to date, finally measuring in at 40.8mm while packing the world’s most powerful movement.