Seiko Prospex GMT SPB381
The Seiko Prospex SPB381 (1968 Diver’s Modern Re-Interpretation GMT) masterfully bridges heritage and modern functionality. With a 42 mm stainless steel case treated with Seiko’s “Super Hard” coating, it retains the angular shoulders and crown-at-four legacy of the original 1968 diver while offering finishing, dimensions (12.9 mm thick, 48.6 mm lug-to-lug), and ergonomics made for today. Its rich green sunburst dial contrasts with a matching green ceramic unidirectional bezel, large LumiBrite-applied markers and hands, and gold accents on the GMT arrow hand and “GMT” text—making for excellent legibility in low light or at a glance above waves. The date sits at the 4:30 position and is balanced by a robust bracelet with diver’s extension and secure clasp. With 200 meters of water resistance, screw-down crown and caseback, and a sapphire crystal with internal anti-reflective coating, the SPB381 is built for both adventure and daily wear.
At its heart is Seiko’s new automatic calibre 6R54, offering approximately 72 hours of power reserve, hand-winding capability, and an independently adjustable GMT hand (often called a “caller” GMT). While not a flying-GMT (local hour jump), this format allows tracking of a second time zone simply and cleanly without compromising the dive-watch identity. The solid construction combines with modern touches—ceramic bezel insert, drilled lugs, hard coating, strong bracelet—to deliver a versatile sports tool for those who value both form and function.
Information:
Pre-Owned: Seiko Prospex Sea GMT SPB381
Reference: SPB381
MSRP: $1500
Bezel Aligns
Strap: Stainless Steel Bracelet
Case Size: 42mm x 12.9mm Thickness 48.6mm Lug to Lug
Lug Width: 20mm
Case Metal: Stainless Steel
Movement: 6R54 - Automatic
Functions: Hours, minutes, seconds, date, GMT
Box and Papers: Box, no warranty papers
Crystal: Sapphire
Bracelet size: 7.5”
Condition:
Case has minimal wear. Bracelet has light normal wear. Dial, hands, and crystal have no wear. Runs within spec.
History of Seiko Watches
Seiko's history began in 1881 when Kintaro Hattori opened a watch shop in Tokyo. In 1892, he established Seikosha, a factory for producing wall clocks. The company quickly progressed, creating Japan's first wristwatch, the Laurel, in 1913. Despite setbacks like the Great Kanto Earthquake of 1923, Seiko persevered, launching its first watch under the Seiko brand name in 1924.
The post-World War II era saw Seiko's rapid growth and innovation. They introduced Japan's first automatic wristwatch in 1956 and launched the prestigious Grand Seiko line in 1960. Seiko achieved international recognition for accuracy in 1968, winning a Geneva Observatory competition.
The company made a name for its divers in 1965 with the introduction of their first professional dive watch, the 62MAS. This was followed by the iconic 6159-7001 in 1968, which was water-resistant to 300 meters. Seiko gained international recognition in 1975 with the release of the 6159-7010, nicknamed the "Tuna Can" due to its distinctive case shape. In 1969, they revolutionized the industry with the Astron, the world's first quartz wristwatch, ushering a new era of watchmaking that would send waves across the industry through the 70s and 80s. From its humble beginnings to becoming a global watchmaking giant, Seiko's history is characterized by resilience, technological advancement, and a commitment to precision.
