Seiko Introduces New Caliber Within Prospex GMT Diver Collection

Seiko ventures into new (and much requested) territory this week with the release of a new collection of GMT divers within their Prospex family. Using their modern 6159 design language seen in watches like the SPB187 with MM200 roots, the new watches strike a fine balance between their roots, and a strong contemporary vision for the range. Seiko has proven quite adept at this in recent years with their restructuring of their dive watch collections, but these latest examples bring something new to the table: a GMT complication within a new 3 day automatic movement, the 6R54. 

The new Prospex GMT diver range welcomes two new references in the SPB381 and 383, and in true Seiko fashion, a single limited edition in the SPB385. Each welcomes the new 6R35 within a steel 42mm case that measures 12.8mm in thickness, and should wear quite similarly to this SPB187 we went hands-on with right here. The angular case gets the distinctive deep chamfer along the lug which has a relatively short overhang to make for a perfectly manageable experience on the wrist.


These watches mark the first time a mechanical GMT movement has made its way into the Prospex dive watch, as the GMT diver is something of a niche genre, and may, to some extent, excuse the fact that this is a caller style GMT execution. The GMT hand can be set independently in one-hour increments, making it a better option for those who work with or communicate with other time zones more than for those who travel between them frequently. You may have been hoping for a modified 6R64 movement here (which features an independently adjustable hour hand), which we’ve seen in similarly priced watches in the Pressage line, but alas, it was not meant to be with these references. We’re still holding out hope. 

The three colorways offer very different interpretations of the platform, with the two mainline references, the SPB381 and 383 bringing green and black, and the 385 offering their glacier blue color and texture paired with a black bezel. The SPB 381 receives a rich green color scheme that extends to the ceramic bezel insert, pairing with the yellow 24 hour hand, and the stoplight tip of the seconds hand. It’s a similar story with the 383 going the full black route.

The SPB385 is limited to 4,000 pieces, and will be priced from $1,700, while the regular production SPB381 and 383 are priced at $1,500. The real question from here is whether or not we’ll see this movement make its way into the 62MAS inspired case, and if a true GMT variant of the 6R64 movement will ever make an appearance within the Prospex family. Expectations will be quite high at these prices, particularly in consideration of the current calibers Seiko has at their disposal. What would make the perfect Seiko GMT diver in your eyes? Let us know in the comments below and keep an eye out for hands-on impressions of this watch coming soon. Seiko.

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Blake is a Wisconsin native who’s spent his professional life covering the people, products, and brands that make the watch world a little more interesting. Blake enjoys the practical elements that watches bring to everyday life, from modern Seiko to vintage Rolex. He is an avid writer and photographer with a penchant for cars, non-fiction literature, and home-built mechanical keyboards.