Seiko Drops Its Best Dive Watch in Years

Seiko is one of the best-known makers of dive watches in the world, with a deep roster and back catalog filled with iconic names like the Turtle, Tuna, Samurai, 62MAS, Monster, SKX and more.

But its latest ranks among the most impressive the Japanese brand has ever produced, and is certainly Seiko’s best dive watch in years.

An update to the 43mm Marinemaster released less than two years ago, Seiko’s latest Marinemaster introduces an array of premium features that place it firmly at the top of the brand’s diver-archy.

Masterful

The new Marinemaster ref. HBF001 is aesthetically quite similar to the ref. SLA079 that launched in September 2024.

Seiko

Both models have the same design inspired by Seiko’s 1968 diver. Both have the same black, grain-textured dial. Both have the same sharply finished stainless steel case measuring 42.6mm in diameter. Both boast sapphire crystals and Lumibrite lume. And both are true ISO-compliant diver’s watches rated to 300m.

So what’s new here, and why does the HBF001 cost an eye-popping $700 more than its slightly older sibling?

Well, there are four big upgrades that you’ll find in the new Marinemaster that weren’t around in 2024.

The first is the bezel insert, which is now made of polished ceramic, replacing the polished steel found in the previous model. This makes the bezel far more scratch-resistant and also gives the Marinemaster a more fitting luxury look comparable to other high-end divers that employ ceramic bezels from brands like Rolex and Omega.

Next is found on the dial. While the handset, dial texture and indices are all unchanged, there’s one change that might make this watch an instant buy for many a Seiko fan: The date window is at 3:00 instead of 4:30. While the crown remains at 4:00, the date has been moved to a white window at 3:00, accented by a small lumed index. It’s a far more symmetrical look and will undoubtedly be one of the most talked-about aspects of this new generation.

Seiko

Next is the clasp. While the bracelet itself is the same design found on the SLA079, the HBF001 introduces a brand-new microadjustable clasp that can resized on the go without the use of any tools. There’s a push-button slider mechanism on the inside, and pressing it gives you a whopping 16mm of travel in 2mm increments. Off the top of my head, I can’t think of another microadjustable clasp on the market offering such a huge size range.

Last, but certainly not least, is another Seiko first making its debut on the HBF001. It’s the brand-new Caliber 8L45, which now ranks as the most accurate mechanical movement offered by Seiko (Grand Seiko doesn’t count).

The new engine is accurate to within -5 to +10 seconds per day (spd), a big improvement over the -10 to +15 spd rating of the Cal. 8L35 found in the SLA079. The 8L45 also boasts a power reserve that’s almost a full day longer, running for 72 hours instead of 50, while still beating at 4Hz. These performance enhancements are made possible by a newly designed mainspring, according to Seiko.

Seiko

The one downside of the new caliber is it is a bit thicker than the outgoing one, which makes the new Marinemaster a little beefier than the 2024 version. The new HBF001 clocks in at 14.1mm thick, up from 13.4mm on the SLA079.

Personally, I don’t mind a bit of thickness in exchange for greater accuracy and a longer power reserve — not to mention a ceramic bezel and microadjustable clasp — but your mileage may vary.

Availability and pricing

If black is too humdrum for you, Seiko has launched a second, special-edition Marinemaster alongside the HBF001. A 1,000-piece limited collaboration with JAMSTEC, the Japan Agency for Marine-Earth Science and Technology, the ref. HBF002 gets the same 8L45 movement, 3:00 date and microadjustable clasp, and a blue instead of black ceramic bezel insert.

Seiko

But the main difference is the dial, which features an intricate three-dimensional texture covered in a stunning blue gradient pattern meant to evoke the tracks left by polar icebreakers, as JAMSTEC is launching the first such vessel for Japan.

Neither the HBF001 and HBF002 Marinemasters will be available until July, but at least we have pricing already. The HBF001 is listed at $3,600, while the JAMSTEC-edition HBF002 goes for $3,900.

Seiko

Seiko Prospex Marinemaster HBF001

Specs

Case Size	42.6mm
Movement	Seiko Cal. 8L45 automatic
Water Resistance	300m

• $3,600 at Seiko

Seiko

Seiko Prospex Marinemaster HBF002

Specs

Case Size	42.6mm
Movement	Seiko Cal. 8L45
Water Resistance	300m

• $3,900 at Seiko

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