The Seiko Marinemaster is something of a legend within the Japanese brand’s impressive back catalog. It represents the high end of Seiko dive watches and has, as a result, become a fan favorite. We have, however, been waiting for something new under the Marinermaster moniker for a while. Also, many of you were hoping for slightly smaller and thinner Seiko divers. Well, my dear Fratelli, consider yourself heard!

This is the brand-new Seiko Marinemaster for 2023, and it comes in three colors. There is a 1,000-piece limited edition in silvery white, the SJE097. Additionally, there are two regular-production models, the black SJE101 and the blue SJE099.

Seiko Marinemaster SJE101

Seiko Marinemaster History 101

Seiko has featured prominently in the dive-watch game since the release of the 62MAS in 1965. It wasn’t until three decades later that the Marinemaster line debuted. The Seiko Marinemaster Quartz SBCN005 came out in the late ’90s.

The first mechanical Marinemaster followed in 2000, with the launch of the SBDX001 and SBDX003. Our own RJ is the proud owner of the 001, and I have to say, it is an amazing watch. Powered by Seiko’s caliber 8L35 and finished with lovely Zaratzu polishing, this Marinemaster was clearly positioned at the top of the (non-Grand) Seiko diver hierarchy. The 300m depth rating — realized, in part, thanks to the monocoque case — backed up that notion.

Seiko Marinemaster SBDX001

One of the SBDX001’s successors, the SBDX023, omitted the Marinemaster name from the dial in exchange for the Prospex “X” logo. The new ones have the X too, but they also feature “Marinemaster” under the Seiko logo.

Seiko Marinemaster SJE097

A new case and bracelet for the Seiko Marinemaster

The new Seiko Marinemaster SJE097, SJE099, and SJE099 feature a brand-new case. No longer monocoque, these are the first Marinemasters with display case backs. The case isn’t quite like the old MM300s, bearing a stronger resemblance to the original 62MAS or some of the later SLA reissues. I suppose that’s why Seiko officially classifies these as Prospex Marinemaster 1965 Diver’s Re-interpretation models. However, the case doesn’t have overly strong vintage vibes. It is a thoroughly contemporary rendition of a familiar shape.

But here comes the big one: it measures 39.5mm across! Yes, my vintage-Seiko-loving friends, you are reading that correctly. Just as importantly, it is just 12.3mm thick, courtesy of the “slimline” 6L37 caliber inside. I saw your comments, Fratelli. I know many of you lamented the large diameters and thick profiles of most Seiko divers. Well, apparently, so did Seiko, and the folks there obliged!

Another novelty is the bracelet. It features brushed outer links and alongside center links with alternating finishes. The resulting look is quite elegant and adds to the modern feel of the watch. The clasp is of the push-button deployant type and features a diving extension. Unfortunately, there is no toolless micro-adjustment system here. On the plus side, though, both the case and bracelet feature Seiko’s hard coating for extra scratch resistance.

Seiko Marinemaster SJE099

Seiko Marinemaster SJE097, SJE099, and SJE101 specs

Beyond the case and bracelet, the first thing to jump out is the new dials. Seiko opted for a horizontally striped pattern. You can have your pick of black (SJE101), light blue (SJE099), or silvery white (SJE097). The last one is fitted with a steel bezel insert and is limited to 1,000 pieces. The other two feature hard-coated lacquered steel bezel inserts. There is a tiny round date window between 4 and 5 o’clock. Naturally, there are rich applications of Lumibrite all around.

As mentioned, inside ticks Seiko’s caliber 6L37. This slimline movement solves the thickness issues that some have with certain Seiko divers. It measures just 3.7mm thick and beats away at a 28,800vph frequency. Seiko’s signature bidirectional Magic Lever automatic winding is present here. You get a power reserve of 45 hours. This new version of the 6L caliber was introduced earlier this year in the 1965 Diver’s Re-creation.

As mentioned, this is the first Marinemaster to feature a see-through case back. Seiko opted to put an image of the Hokusai wave in the center of it. Of course, you get a screw-down crown and a sapphire crystal, here in box style. We will not be calling this the new MM300, though, as its water resistance is rated to 200 meters.

Seiko Marinemaster SJE101 pocket shot

Initial impressions of the new Seiko Marinemaster

There is a lot to like here. I love how these strike a perfect balance between contemporary design and nods to history. These are clearly rooted in a rich dive heritage of dive watches, but they stand on their own as contemporary divers too.

New Seiko Marinemaster case back

Some aspects that leave me less convinced include the striping on the dial, but that is a matter of taste. I tend to prefer simpler dials on dive watches, but your mileage may vary. However, I have a gut feeling that many of you will be with me in disliking prints on display case backs. It looks cluttered and prohibits a proper view of the movement. Either it is worth seeing or it isn’t. If not, I prefer that brands use an all-metal case back with a cool engraving. Lastly, I feel that in 2023, some kind of toolless micro-adjustment could be included in this segment.

I do love how the new Marinemaster focuses on wearability. I don’t mind large Seiko divers; I own and have owned several. But I feel that this size adds versatility to the genre. The new Marinemaster is still perfectly capable as a diver, but it works better in the office now too. Generally, it just feels like a very sensible move in today’s watch market.

Pricing and availability

All three watches will be made available in Seiko boutiques starting this December. The limited-edition silver SJE097 as well as the non-limited black SJE101 and blue SJE099 are all priced at €3,400. For more information, visit the official Seiko website.

What do you think of the new Seiko Marinemaster watches? Are these worthy successors to RJ’s legendary SBDX001 MM300? Let us know in the comments below!

Watch specifications

Prospex Marinemaster 1965 Diver’s Re-interpretation
SJE097 / SJE099 / SJE101
Silvery white (SJE097), light blue (SJE099), or black (SJE101) with horizontal striping, applied luminous indices, and date window
Case Material
Stainless steel with hard coating
Case Dimensions
39.5mm (diameter) × 12.3mm (thickness)
Box-style sapphire with AR coating
Case Back
Stainless steel with display window
Seiko 6L37 — automatic and hand winding, 28,800vph frequency, 45-hour power reserve, 26 jewels
Water Resistance
Stainless steel five-row bracelet with hard coating, diver's safety clasp, and wetsuit extension
Time (hours, minutes, central seconds), date, 60-minute dive bezel
Two years
Special Note(s)
SJE097 limited to 1,000 pieces. All references available as of December 2023.