Seiko Marinemaster: How to Identify this Iconic Dive Watch?

Nov 23, 2020
Seiko Marinemaster: How to Identify this Iconic Dive Watch?

For newbies, the history and evolution of the Seiko Marinemaster can be quite confusing. It’s not so surprising though, given Seiko’s history of naming its watches. Most of its iconic timepieces get their nicknames straight from fans themselves, who gave the names as they deemed fit. Seiko would then adapt the name for later releases. Quite a marketing move, if you ask me. This is a classic strategy to help spread the word about the models. However, this can also be quite complicated for the rookie collector.

While the Seiko Marinemaster remains a fundamental part of Seiko’s growth as a brand, it has quite an intricate evolution. Many people confuse certain models with Marinemaster. Meanwhile, the ones actually labelled as Marinemaster gets confused for other series as well. So, we gathered all the information we can get about the Seiko Marinemaster series.

Everything you need to know about this legendary collection is all here — every model we can find and how to spot one in the wild.

A Brief History of Seiko Dive Watches

It’s no secret how Seiko remains a big player in the dive watch industry. A lot of new collectors look to the brand for entry-level timepieces. The quality factor also plays a huge part in the brand’s reputation among dive enthusiasts. All these began in the 1960s when functional watches took over the world.

Watches served different purposes throughout history. From being a symbol of wealth and power, watches also easily became a functional tool for people from all walks of life. Before Rolex and Omega became collectibles, these brands proved their legacy by putting out functional watches. At the time, deep divers were huge deals as people sought to explore the vast ocean. And so these divers needed timepieces that could keep up with their profession and lifestyle.

Seiko 6159-7001 & Seiko 6159-7001
1. Left: Seiko 6215-7000, Right: Seiko 6159-7001

To keep up with this, Seiko introduced their own line of dive watches starting in 1965. However, it only makes sense to talk about the watch that came out two years later. In 1967, the Seiko 6215-7000 was introduced, but it wasn’t for the faint of heart. Withstanding depths of up to 300 metres, the watch proved iconic for a watch made in the late ‘60s. This water resistance became possible due to the monocoque case or a one-piece case for the watch. It’s also the first Seiko dive watch with a 4 o’clock crown. This trait can be seen in modern-day Seiko dive watches that don’t only provide a signature aesthetic but also a great purpose. After all, it’s easier to access the crown at 4 o’clock rather than 3 o’clock, especially when diving.

The Ref. 6159-7001 followed suit, with almost the same design principle. However, it had a high-frequency movement beating at 36 vibrations per hour. This started Seiko’s high-beat movement speciality. The high frequency and the movements offered not only great accuracy but excellent stability.

To continue the high-end, high-frequency range of timepieces, the launch of the Seiko SBDX001 Marinemaster 300 followed suit. It became a huge hit not only in the Japanese market but also all over the world. And so, the Seiko Marinemaster range was born with great expectations from the market.

Evolution of the Seiko Marinemaster Watches

The evolution of the Seiko Marinemaster goes way beyond just tags and markings on the dial and caseback. We are looking into the design and movements of various Seiko timepieces as we align the Marinemaster legacy right before your eyes. So, we take on the misconceptions and common mistakes people take as a Marinemaster. With this, we present you every Seiko timepiece that goes along the Marinemaster range that collectors love.

Firstly, a new collector must remember this foolproof trick to help you know which Seiko watch is a Marinemaster. Most Seiko PROSPEX watch can be considered a Marinemaster, especially if they meet a depth rating that goes beyond 200 metres. You can find evidence of this either on the dial, the caseback, or even the hangtag from when you purchase a watch in-store. But with the new dynamics of online shopping, we prepared a quick guide to help you identify which ones are Marinemasters according to their model numbers.

A Quick Look at the Seiko Marinemaster Models

The following watches are either explicitly named a Seiko Marinemaster or are an unofficial part of the range:

  1. Seiko SBCN005 Transocean
  2. Seiko SBDX001
  3. Seiko SBDX003
  4. Seiko SLA025
  5. Seiko Prospex SPB077
  6. Seiko SLA021
  7. Seiko Prospex LX SNR029
  8. Seiko SBDB001
  9. Seiko SBDD003
  10. Seiko SBDW015
  11. Seiko SBBN007
  12. Seiko SSBS018
  13. Seiko SBBN011

With that said, let’s take a look at how each of these timepieces became an integral part of the Seiko Marinemaster series — be it a mark on the hangtag or a design choice.

Seiko SBCN005 Transocean & SBDX001

Seiko SBCN005 Transocean & SBDX001 Marinemaster
2. Left: Seiko SBCN005 Transocean, Right: Seiko SBDX001, The Marinemaster

Contrary to popular belief, the Seiko SBDX001 isn’t the first Marinemaster. In fact, the SBCN005 Transocean is the first Marinemaster released by Seiko in the late ’90s. This timepiece includes features such as barometric pressure measurement, as well as a second time zone and alarms. The Seiko SBCN005 Transocean also has a unique case design with a titanium case and a sapphire crystal.

However, as the SBDX001 was launched — it was officially tagged a Seiko Marinemaster 300 with similarities on movement with the Seiko 6215-7000 and 6215-7001. Given that the Ref. 6215-7000 and the 6215-7001 are the predecessors of the whole Marinemaster series, it only makes sense that people mistook the SBDX001 as the first Marinemaster. But with its launch dated to the 2000s, the SBCN005 Transocean remains to be the first Marinemaster in Seiko history.

Seiko Prospex SBDX003 & SBDX005

Seiko PROSPEX SBDX003 & SBDX005
3. Left: Seiko SBDX005, Right: Prospex SBDX003

Launched together under the Seiko Year 2000 Historical Collection, the Prospex SBDX003 and SBDX005 became the next in line for the Marinemaster series. There a few differences between the SBDX001, SBDX003, and SBDX005. Firstly, the SBDX003 is a limited-edition watch that makes it a true collector’s item. Secondly, there are noticeable on the dial designs between the three. The SBDX003 features gold indexes with fewer inscriptions on the dials. Both SBDX003 and SBDX005 omitted the label “Marinemaster” on both dials, which makes it quite hard to identify whether or not they’re actually part of the series. But given the watches’ depth rating and the similar prefix that is the SBDX, it only makes sense that they’re predecessors of the SBDX001 Marinemaster. With that said, the SBDX003 has a water resistance of up to 300 metres, while the 005 models can go as deep as 600 metres. A distinct difference between the 003 and the 004 includes the bezel with a 120-click unidirectional rotating bezel for the former and a 60-click bezel for the former.

Seiko SLA025 & Prospex SPB077

Seiko SLA025, Seiko Marinemaster
4. Seiko 1968 Automatic Diver’s Re-creation Limited Edition Ref. SLA025

If you haven’t caught on it yet, the easiest way to track the Marinemaster line is to start from its legacy watches, the Seiko 6159-70001 and 6215-7000. Seiko truly knew how to take advantage of trends and found the opportunity by reliving these timepieces through a new watch. The Prospex line is taken to greater heights with a vintage-inspired timepiece with modern offerings. Seiko does this by launching the SLA025, a 2018 limited-edition watch.

Aside from leveraging on the classic design cues from the 6159 model, Seiko also made the watch a limited offer by running with only 1,500 editions. The watch, as aforementioned, reapplies the 4 o’clock crown from the Ref. 6159, as well as its case shape. But its movement is a lot more modern with the Seiko Hi-Beat 8L55 movement. This makes complete sense as the Marinemaster series is not only known for incredible water resistance but also its high-frequency movement.

This timepiece became so iconic that it won the Sports Watch Prize at the Grand Prix d’Horlogerie de Genève. You can find the timepiece all over the Internet as it goes by the name 1968 Automatic Diver’s Re-creation Limited Edition.

Seiko Prospex SPB077
5. Seiko Prospex SPB077

Given that the SLA025 is a limited-edition, it does cost quite a lot more. So, if you’re looking into a more affordable option, look no further than the Prospex SPB077. It costs a fraction of the SLA025 but with a similar design. It’s also an open edition version, so while it’s not as rare as the SLA025, it remains a smart choice for those who are looking for quality yet affordable watches. The SPB077 features almost the same vintage feel as the SLA025. But don’t be fooled — it remains to be a modern take on a classic watch. The only downside is that its water resistance isn’t as impressive at 200m, but altogether it’s still very functional!

Seiko Prospex SLA021

Seiko Prospex SLA021, Seiko Marinemaster
6. Seiko Prospex SLA021

There are certain timepieces, especially from the Prospex line, that don’t specifically label as a Marinemaster. That’s why the Seiko Marinemaster range can be quite a confusing line, to begin with. However, as we follow the series’ legacy, we find that the easiest way to identify a Marinemaster is by tracing a watch’s design roots and movement base. That’s why, despite not being specifically called a Marinemaster, the Seiko Prospex SLA021 remains a vital part of the range. Unsurprisingly so, it features everything great about the modern-day Prospex specs but with a close — if not direct — resemblance with the SBDX001.

While the model closely resembles the SBDX001, it has modern features that are perfect for the rough seas. One of those includes the change in the bezel insert. The usual aluminium bezel insert from the previous Seiko diver models has been changed to ceramic for better protection. It also enforces the Seiko Zaratsu polishing techniques that give them a sheen that’s mirror-like. The watch is the perfect representation of refined luxury that a Seiko watch can also provide, despite it being one of the more affordable ones in the market compared to luxury Swiss brands.

Seiko Prospex LX SNR029

Seiko Prospex LX SNR029, Seiko Marinemaster
7. Seiko Prospex LX SNR029

Seiko launched the Prospex LX collection in 2019, and with it came the SNR029. A quick Google search can bring you just as confusing results as the Marinemaster’s range. But the reason we put this here basically lies in its great similarity with the SLA021 and the designer’s fascination with the Marinemaster series.

Industrial designer Ken Okuyama crafted the SNR029. He specifically mentioned taking inspiration from the Marinemasters of the past for this timepiece. That’s why it dramatically resembles the SLA021. This GPHG award-winning Prospex boasts its prowess right at the dial. The watch’s power reserve indicator, as well as the “Spring Drive” signature on the dial, gives the watch the ultimate bragging rights. Spring Drive took Seiko as well as the watch industry to greater heights. It has an accuracy of +/-1 second per day. That’s +/- 15 seconds per month! This kind of accuracy is achieved through the combination of a mechanical gear train with an electronic time regulation. Basically, you get an electronic and mechanical movement in one.

The SNR029 features almost the same Marinemaster bezel as seen on the SLA021. The unidirectional titanium bezel has a luminous green glow from the 12 o’clock triangle up until the 20-minute marker. The matte dial of the watch also helps with legibility especially when underwater as it doesn’t reflect any light. As expected, it also has a Zaratsu finish on its metal trims. All these details make the SNR029 such an iconic timepiece. It’s lightweight in physical features but a heavyweight when it comes to movement and function.

Other Seiko Marinemaster Watches

We’ve gotten through the crucial parts of the list. Now, let’s take a look at other timepieces that are considered Marinemasters not only by Seiko but also by the community itself.

As aforementioned, the rule of thumb when it comes to identifying Marinemasters is checking a watch’s depth rating. Any depth rating more than 200 metres — 300m, 600m, or even 1000m — counts heavily as criteria. These include the SBDW015, SBBN011 1000m Darth Vader shrouded diver, and the SBDD003. However, a watch being under the Prospex line makes it a definite Seiko Marinemaster. It will be safe to assume that all Prospex watches with a depth rating of 300 metres or more are Marinemasters. While it doesn’t say so on the case or dial, others feature it on the hangtag when being bought in store as with the case of the Seiko SBBN007 and SSBS018.

A noticeable trait of the Seiko Marinemaster also includes design choices. If it resembles the original Marinemasters (6159 and 6215) or any other Marinemaster we’ve mentioned in the list, then it most likely belongs on the range, same as with the watch’s movement. An excellent movement marks the greatness of the Seiko Marinemaster. This is characterised by a high-frequency movement or in select cases, a Spring Drive movement. Both the Hi-Beat and Spring Drive movements are part of the reasons why Marinemasters are iconic to this day.

We hope this article clarified any confusion about the collection and help you decide which Seiko timepiece you’re about to add to your prized collection.


Want to learn more about Seiko’s iconic dive watches? Check out our review of the Seiko Sea Urchin and Seiko Turtle!

Photo credits: 1 | 2 | 3 | 4 | 5 | 6 | 7

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