Grand Seiko’s newest diver’s watch takes aim at both accuracy and wearability. The Spring Drive U.F.A. Ushio 300 Diver, available in blue or green, introduces the brand’s ultra‑fine accuracy calibre 9RB1 into a compact 40.8 mm high‑intensity titanium case.
The movement is a tuned version of the U.F.A. calibre introduced last year and achieves ±20 seconds per year by vacuum sealing the quartz oscillator, thermally compensating the movement and regulating it against a reference signal. A 72‑hour power reserve and 300‑metre water resistance mean the watch is ready for serious diving or daily wear.
The Ushio, named after the Japanese word for tide, features a gradient dial with a wave motif that captures the way light dissipates underwater. Diamond‑cut indices and hands coated in LumiBrite ensure legibility. A unidirectional ceramic bezel has a 120‑click mechanism and scratch‑resistant insert.
The redesigned power‑reserve indicator is repositioned to the case back, leaving the dial cleaner, and the locking extension clasp allows micro‑adjustments without removing the watch.
At just 12.9 mm thick and 48.5 mm lug‑to‑lug, it is the most compact 300‑metre diver Grand Seiko has ever produced. Deliveries begin in June 2026 through Grand Seiko boutiques and selected retailers.
