Founded in 1881 in Tokyo, Japan, Seiko is known for its in-house manufacturing, technical innovation, and professional-grade dive watches. The Marinemaster collection represents Seiko’s highest standard in mechanical diver’s watches, built for extreme reliability and performance.

The Seiko Marinemaster 300 Blue, reference SLA023J1, is a professional diver’s watch designed for serious underwater use. The watch features a 44.3 mm stainless steel case paired with a deep blue dial. Large luminous indexes, bold hands, and excellent legibility define its tool-focused character.

Powered by the in-house Seiko caliber 8L35 automatic movement, it offers a 50-hour power reserve, a frequency of 28,800 vph, and functions including hours, minutes, seconds, and date.

A sapphire crystal with anti-reflective coating protects the dial, while the unidirectional stainless steel bezel supports precise dive timing. Water resistance is rated at 300 meters. The watch is fitted on a stainless steel bracelet with a folding clasp, and includes no additional strap.

This Marinemaster 300 Blue is in good condition and comes as a full set.