Functional, easy to use, and beautiful. The Evolution 9 Collection’s Ushio 300 Diver was conceived with these ideals in mind. What makes a diver’s watch that pushes the limits of its movement, design, and finish so compelling?

A Spring Drive diver’s watch forged through a legacy of innovation

Since the brand’s inception, Grand Seiko has continuously challenged itself to innovate. It was during this process that the new design code of the Evolution 9 Style emerged in 2020, with the Evolution 9 Collection created to embody this philosophy and serve as a symbol of the modern Grand Seiko.
This collection has been developed to take Grand Seiko’s three prized values of functionality, wearability, and aesthetics to a higher level, and the new Ushio 300 diver’s watch seems as if it was destined to take its place among this lineup.
To qualify as a “diver’s watch,” a timepiece must adhere to several strict criteria, among them legibility, water resistance, and operability. Effectively balancing these requirements at a high level is deeply ingrained in Grand Seiko, and this quality can be observed in the watches that the brand has created over the years. Meeting rigorous standards has been essential to expanding Grand Seiko’s potential. The Ushio 300 model was created to bring a new dimension to the Evolution 9 Collection.

 

Grand Seiko Evolution 9 Collection

Spring Drive U.F.A. movement derived from the perspective of functionality

Grand Seiko’s proprietary 9R Spring Drive movement is powered by a mainspring yet controlled by a quartz oscillator and integrated circuit (IC). Unlike purely mechanical watches, Spring Drive has been designed without a balance wheel or pallet fork, allowing for excellent shock resistance. And yet there is no need to worry about running out of battery power. These characteristics are highly compatible with the performance required of a sports watch. For this reason, the diver’s watches in the Evolution 9 Collection have used Spring Drive movements before.
This approach was carried over to the Ushio 300, and as a new challenge, Grand Seiko developed the Caliber 9RB1, a Spring Drive U.F.A. (Ultra Fine Accuracy) movement with an annual rate of ±20 seconds. While this variation of the Caliber 9RB2 introduced in 2025 has the same basic design, the power reserve indicator has been moved to the dial side. This was the result of adopting a closed case back to reduce entry points for water. However, this also allows the amount of power left in the mainspring to be monitored at any time, even when actively diving. 
The unidirectional rotating bezel, used to measure the elapsed diving time, is also designed with functionality in mind. The bezel insert is made of highly scratch-resistant ceramic, and the numbers and scales are gray in color. This design was conceived to provide a visual balance with the LumiBrite hands and indexes and to avoid interfering with the legibility of the dial.

Though diver’s watches have been refined over their long history, there is, nevertheless, still room for further development. With the Ushio 300 Diver, the aim was to achieve a more practical watch with enhanced functionality through technology and design.

Pursuing wearability in step with daily life

In a watch, wearability is of great importance. In a diver's watch, worn in environments where dependability is a matter of safety, it is all the more important to have a secure fit. The Spring Drive U.F.A. Caliber 9RB1 in the Ushio 300 Diver has a diameter of 30.0 mm, smaller than previous Spring Drive movements, and a thickness of 4.7mm despite its automatic winding. Owing to this compact movement design, the Ushio 300 has a case diameter of 40.8 mm and a case thickness of 12. 9 mm. Its relatively small size for a diver’s watch with 300 meters of water resistance allows it to sit comfortably on the wrist.
Additionally, the materials used for the exterior and bracelet have also been carefully considered to improve wearability. The case and bracelet are made of lightweight and highly corrosion-resistant High-Intensity Titanium. The clasp features a diver’s extension and a fine-adjustment mechanism, allowing the bracelet to be extended by a total of 24 mm. These subtle refinements all combine to achieve a comfortable fit.
While the case is on the smaller side, it is highly durable, and consideration was given to ease of maintenance, such as re-polishing. The case design, which has been made slightly more robust to complement the large and legible insert of the unidirectional rotating bezel, captures the reflection of light on its wide surfaces to evoke a form that is striking.
While designed with comfort in mind, this creation also asserts the robustness of a diver’s watch.

Aesthetics that enriches the heart

The aesthetics of the Evolution 9 Collection are most clearly revealed in the appearance of the dial.
The Ushio 300 features an iconic patterned dial to add originality while ensuring the performance of a diver’s watch. The ushio motif (the term means “tide” in Japanese) is inspired by the ocean currents that bring abundant natural blessings to the Japanese archipelago. Its texture evokes powerful and dynamic rolling waves. Various expressions of the sea surrounding Japan are integrated into the color of each model’s dial, with the blue variation evoking powerful, intense ocean swells while green conveys the calm tranquility of coastal waters. These beautiful dials capture the passage of time through the fluid motion of their seconds hands, made uniquely possible through Spring Drive.
Each dial features a color gradient that deepens toward the outer edge. This was done to highlight the beauty of the dial pattern at the center and enhance the legibility of the indexes by darkening the color of the outer ring, while also giving a sense of spaciousness to the dial as a whole.
The shapes of the indexes have been changed from round to square. By crafting the indexes as individual components, angled cuts can be made to cast a delicate glow. Of course, to prevent the indexes from coming loose, they have been fixed to the dials manually by craftsmen.
The aesthetics of the Ushio 300 Diver were ultimately created to ensure the legibility and functionality expected of a diver’s watch. In doing so, its beauty strikes just the right chord with users. This captures the essence of Grand Seiko’s evolution and is the realization of the Evolution 9 Collection.

The Ushio 300 diver’s watch, featuring the Spring Drive U.F.A. Caliber 9RB1 with an annual rate of ±20 seconds, is a high-performance model with 300-meter water resistance for air diving. It boasts the compact case size of 40.8 mm for enhanced wearability. In keeping with the Evolution 9’s philosophy of functionality, wearability, and aesthetics, the meticulous detailing and design give this watch its unique style.

Photography (Portrait): Yoshiaki Tsutsui
Photography (Still Life): Hiroki Watanabe
Styling: Nobutaka Kobayashi
Hair: SHOTARO (SENSE OF HUMOUR)
Models: KEN MORITA (HOLDER), TAKU HAYASE (HOLDER)
Text: Tetsuo Shinoda
Editor: Yuji Kuramochi