Introducing: The Seiko Prospex Marinemaster SLA081 — Marking The 60th Anniversary Of Seiko Dive Watches
Seiko regularly surprises us with new limited editions. Typically, they are variations of existing models that introduce new dials and eye-catching colors. But sometimes, a limited series is more than that. With the introduction of today’s new trio of watches, Seiko treats us to a few firsts that fans will certainly love. The most important news is the release of the Seiko Prospex Marinemaster SLA081. It’s a new high-end titanium Marinemaster model based on the brand’s 1968 Diver. On top of that, we get the new SPB511, a variation of the popular modern take on the 62MAS, as well as the SPB509, another version of the Prospex GMT diver. Let’s find out more!
Before we get into the specifics of each of the three models, the overarching theme here is beautiful wave dials. Seiko has knocked it out of the park with these. The dark blue dials for the SLA081 and the SPB509 are especially nice. They add depth and texture to these limited editions, making them stand out immediately. We all know that Seiko and Grand Seiko introduce a great number of new dials every year, so for these to make such an impact is special. Let’s discuss them by zooming in on the three new models.
Seiko Prospex Marinemaster SLA081
Let’s kick things off with the big kahuna. The new Seiko Prospex Marinemaster SLA081 immediately stands out from the other two watches. But once you pick it up, you will be surprised because it is lighter than you may have initially thought. The watch features a 45.4mm titanium case with a 16mm thickness and a relatively reasonable 50mm lug-to-lug.
It is a monobloc case with an L-shaped gasket to prevent helium infiltration, eliminating the need for an escape valve and making this watch suitable for saturation diving. This construction is a nod to the first-generation professional “Tuna” divers introduced in 1975 and the reason Seiko added the word “Professional” to the dial. Overall, it is an impressive case modeled after that of the brand’s 1968 diver, so it also looks like the Marinemaster 300 SBDX001 that our readers know and love.
Based on its dimensions, it is fair to state that this is a big watch. However, thanks to the lightweight titanium, it certainly doesn’t feel like it. The case features a titanium bezel with a stainless steel insert treated with a DLC (diamond-like carbon) coating and bearing engraved numerals and markers in white.
Seiko combined the case with a beautiful dark blue gradient dial with an intricate wave pattern mimicking the great depths of the sea. I love the blue shade that Seiko chose because it oozes style and further emphasizes the watch’s aquatic inspiration. The dial features contrasting indexes treated with Seiko’s Lumibrite for great readability in the dark.
A new bracelet and black DLC bumpers for the SLA081
Completing the look is the new five-row titanium bracelet. That’s also where it gets interesting. As you can see, between the end links and the case are two black DLC-coated stainless steel parts that affix the bezel and keep it in place. These bumpers are mounted on the case back and make servicing the watch with its monobloc case a lot easier.
It’s an interesting choice that works well for its intended purpose. If I had designed this watch, I wouldn’t have made the bumpers black, but it makes sense since the color of stainless steel is different from that of titanium. The new bracelet itself has more rounded links and also features a re-engineered clasp with a dive extension and an extra fold-over lock.
Inside the case, Seiko equips the SLA081 with its brand-new in-house caliber 8L45. It operates at 28,800vph, has 35 jewels, and offers 72 hours of power reserve. The caliber incorporates Seiko’s proprietary Spron alloy. This material was designed for durability against breakage, rust, and wear, ensuring resilience in harsh underwater conditions. Thanks to a thinner, longer mainspring, the power reserve has increased over that of the previous 8L35. The new 8L45 movement also has an officially stated accuracy of -5/+10 seconds per day.
This new Seiko Prospex SLA081 is an impressive professional dive watch that is surprisingly easy to wear thanks to its lightness. Seiko will produce 600 pieces of this limited edition, which will be available worldwide starting July 2025 for €4,900.
SPB511 (left) and SPB509 (right)
The new Seiko Prospex SPB509 GMT diver
In addition to the new high-end Prospex Marinemaster, Seiko announced two more 60th-anniversary models that are variations of popular Prospex dive watches. The first is the SPB509, a GMT version of the 1968 Diver’s Modern Re-interpretation.
As such, it is related to the SPB381, SPB383, and SPB385 GMT dive watches that Seiko released in 2023. The SPB509 has a 42mm case with a 13.3mm thickness and a 48.8mm lug-to-lug. This stainless steel case features a super-hard coating and a 300m depth rating (a 100m improvement compared to the previous models).
Topping the case is a beautiful dark blue bezel insert that matches the stunning blue wave dial. You may have noticed that this motif is different from that of the SLA081 and features much more prominent waves. I have to give Seiko a big compliment for choosing two shades of blue that work incredibly well with these dials. They echo the depths of the sea and give them instant purpose.
Contrasting the blue dial are 12 large hour markers filled with Lumibrite. The silver-colored hands indicating the local time are combined with a short gold-colored GMT hand that indicates the time in another time zone. This hand’s corresponding 24-hour scale is on the rehaut of the dial, helping it fit nicely into the design without interfering with the watch’s diving purpose.
As with previous releases, the crown is on the right side of the case, just above the 4 o’clock marker. Seiko subtly integrated the date window between 4 and 5 o’clock, so it doesn’t stand out unless you focus on it. To me, that is exactly how a date window should be on a functional tool watch like this one.
A new clasp that Seiko fans will love
Last up for the exterior, the new bracelet finishes the look nicely. This three-row bracelet comes equipped with a new clasp that should be a hit with fans. Finally, Seiko answered the call for a new clasp with a toolless micro-adjustment system. But the brand has done more than just integrate that for quicker sizing. The new milled clasp is nice and thin and looks super sleek. As a result, many fans will welcome this change with open arms.
Hiding behind the steel case back is Seiko’s in-house caliber 6R54. This automatic GMT movement operates at 21,600vph and offers 72 hours of power reserve. The caller-style GMT movement allows you to independently adjust the 24-hour hand. No, it is not a much-desired flyer-style movement, but unless you travel across time zones often, there are no major downsides to a caller-style GMT caliber. Seiko will produce 6,000 pieces of this second 60th-anniversary model, which will retail for €1,900 starting in June 2025.
The new Seiko Prospex SPB511
The last of the three new models is the Seiko Prospex SPB511. This watch is based on Seiko’s modern interpretation of its famous 62MAS. As some of you will know, the latest iteration of that series debuted about a year ago, and Thomas wrote about it here. Before that was the first series of modern 62MAS-style divers, which included the highly popular SPB143.
This new Seiko Prospex SPB511 features a 40mm stainless steel case with a 13mm thickness and a 46.3mm lug-to-lug. Just like the SPB509 GMT, the case and bracelet have received a super-hard coating, and the watch has a 300m depth rating.
The case features a unidirectional stainless steel bezel holding a gray insert with white numerals and markers. It complements the silver wave dial so nicely. This one has the same pattern as the blue dial in the SPB509. For those wondering, Seiko took inspiration for this from the wave image found on the back of many of the brand’s dive watches.
A new sleeker clasp for a better overall look
The combination of the silver dial and dark gray bezel immediately makes this SPB511 stand out. The hour markers blend in somewhat with the dial color, but the slightly different hue of the Lumibrite brings a slight color difference. Finishing the watch’s look is a three-row bracelet that also features the new clasp.
This new clasp especially works miracles for this new model. As this is the sleekest of the three, it also benefits the most in terms of overall profile. It makes the watch look better, and fans will love the improved functionality.
Powering this watch is the in-house Seiko caliber 6R55. This automatic movement operates at 21,600vph and provides 72 hours of power reserve, just like the 6R54 GMT movement. Its indicated accuracy is -15/+25 seconds per day.
Just like the SPB509, the new SPB511 will be available starting in June 2025. The watch is a limited edition of 6,000 pieces and will retail for €1,500. It is the first variant in the current 62MAS-based line that features a light-colored dial. Of course, that is nothing new, but it’s great to see how nice it looks. It shows the power of the original 62MAS design and how Seiko managed to turn that into a modern daily wearer.
Final thoughts on the new Seiko Prospex 60th-anniversary divers
Seiko did a great job with this new trio of 60th-anniversary dive watches. My favorite is the SLA081 because it is seriously impressive. Despite its grandiose presence, the SLA081 is lightweight, and it brings back the great look of the most famous Marinemaster models. As a result, it hits precisely the right note. Plus, the monobloc construction is nothing short of brilliant. Part of the newly constructed case is the L-shaped gasket to prevent helium infiltration. It’s a subtle nod to the legendary “Tuna” that also celebrates its anniversary this year. That’s why we hope Seiko will also reveal a 50th-anniversary Tuna model in the coming months. For now, the SLA081, SPB509, and SPB511 are a great start to this year of anniversaries for Seiko dive watches!
