Prospex Marinemaster 1968 Heritage JAMSTEC Limited Edition

Inspired by the routes carved by polar icebreakers

Seiko’s legacy of testing the limits of the modern sports watch and supporting marine conservation continues through its partnership with the Japan Agency for Marine-Earth Science and Technology (JAMSTEC), which began in the 1980s. In 1983, two professional diver’s watches rated to 600 meters were successfully tested aboard the SHINKAI 2000, a manned research submersible which was operated by JAMSTEC.

Inspired by the spirit of bold exploration that connects JAMSTEC and Seiko, a new limited-edition diver’s watch joins Prospex’s flagship Marinemaster series.

The design features a blue ceramic bezel that enhances the beauty of the dial while providing exceptional scratch resistance. With Caliber 8L45, Seiko has improved the shape and design of the mainspring and implemented precise accuracy adjustments, achieving the highest accuracy (-5 to +10 seconds per day) among Seiko’s current mechanical movements and a power reserve of approximately 72 hours.

The dial’s new three-dimensional pattern takes inspiration from the tracks carved through sea ice by icebreaking vessels. Its blue gradient, which deepens toward the center, combines with a thick, transparent coating that is meticulously polished to create exceptional clarity and depth. Together, these elements evoke the pure, profound blue that emerges within the Arctic Ocean, revealed amidst the vast expanse of drifting sea ice.

The watch features an updated clasp that offers easy adjustments of up to 16mm in 2mm increments by sliding the button inside. Even when the clasp is closed, the extension can be retracted, ensuring comfortable and effortless operation.

Limited edition of 1,000 pieces

Specifications:

• Case: 42.6mm Stainless Steel with LIMITED EDITION on the case back (14.1mm thick, 49.3mm lug-to-lug)
• Movement: Caliber 8L45 (Automatic with manual winding)
• Power Reserve: Approx. 72 hours(3 days)
• Jewels: 35 Jewels
• Frequency: 28,800 vibrations per hour (8 beats per second)
• Functions: Stop second hand function, date display
  
• Bezel:  Stainless steel unidirectional rotating bezel with ceramic display
• Crystal: Dual-curved sapphire with anti-reflective coating on inner surface
• Dial: Blue gradient with three-dimensional pattern, LumiBrite on hands and index(es) 
• Water Resistance: 300m / 1000ft diver's
• Magnetic Resistance: 4,800 A/m
• Crown: Screw-down crown
• Case Back: Screw-down
• Strap/Bracelet: Stainless steel bracelet with three-fold clasp ＆push button release, solid & slide adjuster