Inside The New Grand Seiko Spring Drive U.F.A. Ushio 300 Diver

Grand Seiko expands its professional dive watch lineup with the new Spring Drive U.F.A. Ushio 300 Diver models, references SLGB023 and SLGB025. These releases mark a significant evolution in the brand’s approach to dive watches, combining more compact proportions, improved ergonomics, and a groundbreaking movement.

A More Compact and Wearable Titanium Case

One of the most notable updates is the redesigned case. Both models feature a High-Intensity Titanium construction, a material known for its strength and reduced weight compared to stainless steel, making the watch more comfortable for extended wear.

The case measures 40.80 mm in diameter and 12.90 mm in thickness, proportions that represent a clear shift toward greater wearability without compromising performance. The watch is water-resistant to 300 meters and features a solid screw-down caseback, reinforcing its credentials as a true professional dive instrument.

The bracelet, also crafted from High-Intensity Titanium, has been reworked with practicality in mind. It incorporates a three-step micro-adjustment system, allowing for incremental changes of 2 mm per step, totaling 6mm of fine adjustment. In addition, a built-in diving extension of 18mm ensures the watch can be comfortably worn over a wetsuit when needed.

Ushio Dial Design: Inspired by Ocean Tides

Both references adopt the brand’s “Ushio” dial pattern, a textured design inspired by the movement of ocean tides. The SLGB023 comes with a deep blue gradient dial, while the SLGB025 features a rich green gradient variation.

The dials offer a strong sense of depth while maintaining excellent legibility. Applied indices are larger and more defined than previous generations, and they are filled with Lumibrite to ensure visibility in low-light or underwater conditions.

Complementing the dial is a unidirectional rotating bezel with 120 clicks, fitted with a ceramic insert that enhances scratch resistance. The bezel’s darker tones are carefully matched to the dial, creating a cohesive overall aesthetic.

Caliber 9RB1: Ultra Fine Accuracy (U.F.A.)

At the heart of these models is the new Spring Drive Caliber 9RB1, featuring the U.F.A. (Ultra Fine Accuracy) designation.

This movement delivers an impressive accuracy of plus or minus 20 seconds per year, making it one of the most precise calibers powered by a mainspring. By combining mechanical energy with quartz regulation, the Spring Drive system ensures both exceptional precision and the signature smooth sweeping seconds hand.

Another key advantage of the Caliber 9RB1 is its compact construction, which has allowed Grand Seiko to reduce the overall case size of the watch—an important development for the brand’s dive watch segment.

Built for Performance

These new Ushio divers are designed to meet the demands of professional use. The 300-meter water resistance provides confidence in serious diving environments, while the screw-down crown and caseback contribute to overall durability and water-tightness.

Legibility has been prioritized through the use of bold hands and generously applied Lumibrite on the indices, ensuring clarity in dark or murky conditions. The ceramic bezel insert further enhances durability, offering strong resistance to scratches and wear over time.

Price and Availability

The Grand Seiko Spring Drive U.F.A. Ushio 300 Diver SLGB023 and SLGB025 are priced at € 12,500. This positions them competitively within the high-end dive watch category, particularly when considering the combination of titanium construction, refined finishing, and the advanced Spring Drive movement.

Final Thoughts

With these new references, Grand Seiko refines its approach to the modern dive watch. The more compact case dimensions, improved bracelet functionality, and the introduction of the highly accurate Caliber 9RB1 result in a watch that successfully balances professional specifications with everyday usability.

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General Specifications:

Brand: Grand Seiko

Model: Spring Drive U.F.A. Ushio 300 Diver

Reference: SLGB023, SLGB025

Dial: Blue (SLGB023), green (SLGB025)

Case Material: High-Intensity Titanium

Case Dimensions: 40.80 mm Diameter, 12.90 mm thickness

Crystal: Sapphire glass

Case Back: High-Intensity Titanium

Water Resistance: 300 Meters

Strap: High-Intensity Titanium bracelet with three-step micro-adjustment and dive extension

Calibre: 9RB1 UFA

Dimensions: 30 mm Diameter, 4.70 mm thickness

Functions: Hours, minutes, seconds, power reserve indicator

Winding: Automatic

Jewels: 33

Power Reserve: 72 hours

Price: € 12,500

Availability: Now

Limited Edition: No