Introducing Seiko Announces More Dive-GMTs With The Prospex GMT SPB381, SPB383, and SPB385


When your birthday happens to land in March, it can be challenging to disavow oneself from the notion that any one of the exciting new watch releases is somehow connected to your big day. At least, that's how I felt when I saw that Seiko has just uncovered a new GMT model range for their sporty Prospex collection that not only has Marine Master-derived good looks, but is also a proper dive-GMT. Do you smell birthday cake? Just me? 

The Seiko Prospex SPB385, SPB383, and SPB381 (left to right). 

Above, you can see the three references that make up the line of the Prospex 1968 Diver's Modern Re-interpretation GMT and Seiko Watchmaking 110th Anniversary Seiko Prospex Save the Ocean Limited Edition. The LE is the SPB385 and it's above left, then the black dialed SPB383 is in the middle and the green SPB381 is on the right. All three versions are 42mm wide, 12.9mm thick, 48.6mm lug-to-lug, and have sapphire crystals, drilled lugs, ceramic bezel inserts, and a date tucked between the four and five-hour markers. 

That date, and the rest of the functions, are all supported by a brand new movement, the Seiko 6R54. This automatic movement offers not only an impressive 72-hour power reserve, but also one of the SPB38X's core features, an independent 24-hour GMT function. Sometimes called a "caller" GMT, this style of tracking a second time zone functions by allowing the user to independently adjust the GMT hand via the crown to indicate against a 24-hour scale surrounding the dial. 

Pricing for the two nonlimited references (the SPB381 and 383) is $1,500, while each and every one of the 4,000 pieces Seiko is making of the SPB385 will retail for $1,700. All three come on a hardened steel bracelet and availability is slated for June/July 2023 at select retailers. 

What We Think

Lately, I've been voicing my appreciation for dive-GMTs to just about anyone who will listen. The combination is one of considerable appeal as it blends the sort of watch I want to use while traveling (a GMT) with the sort of watch I want on my wrist wherever I am headed (a dive watch). And Seiko is on a bit of a roll here as these new mechanical GMTs are announced only weeks after the launch of the new Solar GMT Seiko "Sumos" (which offer excellent value for a "flyer"-style GMT). 

Looking specifically at these new SPB38X variants, I think Seiko has a homerun on its hands. The sizing is entirely reasonable (especially with a sub 49mm lug-to-lug), the specs are solid, the looks are classic Seiko diver with an extra helping of the sort of design language that we've seen on Marine Masters and even some elements from Grand Seiko. Top it off with a trio of attractive colorways and ceramic bezel inserts, and pricing that starts at $1,500, and it would appear that you're getting an awful lot for your money here in a handsome everyday sports watch. 

While I'll go ahead and agree with some of the future comments in saying that I do wish they had created the new movement with a local jumping GMT feature (commonly called a "flyer" GMT), I don't mind a "caller" GMT, especially if your main need for the function is to track a second timezone while you're at home (rather than the inverse). But the price ceiling for flyer GMTs has come way down over the past several years and it offers direct benefits for those actively changing time zones. As it is, for only a few hundred dollars more than the average retail price of an SPB diver, you get a GMT, too. 

Birthday-related narcissism aside, I am very excited to see one of these new dive-GMTs in the metal as it feels like the sort of watch folks have been asking Seiko to make for quite some time. Expect more as soon as I can get my hands on one. 

The Basics

Brand: Seiko
Model: Prospex 1968 Diver's Modern Re-interpretation GMT and Seiko Watchmaking 110th Anniversary Seiko Prospex Save the Ocean Limited Edition
Reference Number: SPB381 (green), SPB383 (black), SPB385 (light blue, LE)

Diameter: 42mm
Thickness: 12.9mm
Lug to lug: 48.6mm
Case Material: Steel with Seikos super-hard coating
Dial Color: Green, black, or light blue
Indexes: Applied
Lume: Lumibrite on hands and markers
Water Resistance: 200 meters
Strap/Bracelet: Steel bracelet

The Movement

Caliber: Seiko 6R54
Functions: Hours, minutes, seconds, GMT (24 independent, aka, "caller" style)
Diameter: 27.4mm
Thickness: 5.3mm
Power Reserve: 72 hours
Winding: Automatic
Frequency: 21,600 VPH
Jewels: 24 

Pricing & Availability

Price: SPB381 (green) and SPB383 (black) – $1,500. SPB385 (light blue) – $1,700
Availability: Select retail locations starting June/July 2023
Limited Edition: SPB385 is limited to 4,000 units


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