Grand Seiko Releases Its Smallest Dive Watch Yet With the Spring Drive U.F.A. Ushio 300 Diver
Watches and Wonders 2026
Grand Seiko is once again a highlight of Watches and Wonders 2026, this time with the introduction of a new generation of its Spring Drive dive watch, unveiling the Evolution 9 Collection Spring Drive U.F.A. Ushio 300 Diver. The release builds on the debut of the U.F.A. (“Ultra Fine Accuracy”) designation introduced by the brand in 2025, now pairing that high-precision Spring Drive technology with a more compact case format. At 40.8mm, the new model also notably becomes the smallest Grand Seiko diver to date, while also representing the most accurate mainspring-powered wristwatch currently offered by the brand.
The new Ushio 300 Diver is housed in a 40.8mm case measuring 12.9mm thick, marking a significant reduction in size compared to previous Spring Drive divers in the lineup. Both the case and bracelet are crafted from High-Intensity Titanium, a material that according to the brand is approximately 30% lighter than stainless steel while maintaining strong resistance to corrosion and wear. Despite the reduced dimensions, the watch retains a robust presence on the wrist, aided by broad, flat surfaces designed to catch and reflect light. The case is water-resistant to 300 meters and features a screw-down crown and solid caseback.
A unidirectional, 120-click bezel with a ceramic insert provides durability and precise timing functionality, while the bracelet introduces a newly developed clasp system with micro-adjustment. The clasp allows for 6mm of fine adjustment in three steps, along with an additional 18mm extension designed for use over a diving suit.
The watch is offered in two dial variations, both based on Grand Seiko’s “Ushio” design language. The term ushio, meaning “tide” in Japanese, informs the textured pattern and gradient coloration of the dials, which are available in blue and green executions. The blue version, ref. SLGB023 evokes deeper ocean tones, with a gradient effect that suggests light penetrating the water, while the green dial ref. SLGB025 draws inspiration from shallower coastal environments. In both cases, the pattern works to enhance depth while maintaining legibility.
Applied indexes follow the Evolution 9 design principles, with sharply faceted surfaces and diamond-cut edges to maximize light reflection. Generous applications of Lumibrite ensure visibility in low-light conditions, while the hands are shaped for immediate readability. The power reserve indicator has been repositioned to the dial side, integrating more cleanly into the overall layout.
Inside is the new Spring Drive caliber 9RB1, an evolution of the U.F.A. format first introduced with caliber 9RB2. The movement delivers an annual accuracy of ±20 seconds, or roughly ±3 seconds per month, making it the most precise mainspring-powered movement currently offered by Grand Seiko.
According to the brand, this level of precision is achieved through a combination of mechanical and electronic regulation. The crystal oscillator is vacuum sealed alongside the integrated circuit to minimize the effects of temperature, humidity, and other environmental factors, while each oscillator undergoes a multi-month aging process and is individually calibrated.
The movement is hand-assembled at the Shinshu Watch Studio and features a 72-hour power reserve, 33 jewels, and a regulation system that allows for long-term accuracy adjustment during servicing.
Pricing
The Grand Seiko Spring Drive U.F.A. Ushio 300 Diver is priced at $12,400, both for the ref. SLGB023 and the ref. SLGB025. The models will be available beginning in June 2026 through Grand Seiko boutiques and select retail partners worldwide.
To learn more, visit Grand Seiko, here.
