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In-Depth – Seiko Prospex Marinemaster 1000m “Emperor Tuna” Ref. SBDX014 – The Japanese Kraken

| By Brice Goulard | 12 min read |
Seiko Prospex Marinemaster 1000m Emperor Tuna Rose Gold SBDX014

Seiko’s reputation in the field of dive watches is hard to beat. While they may not have been behind the creation of the first dive watch, the contributions of Seiko in improving the concept of a timekeeping instrument for divers is immense. Many features that are now the norm for dive watches were created under the influence of Japanese engineers – Seiko even influenced the creation of the ISO 6425 standard for dive watches. So, with over 50 years of innovation, over 50 years creating professionally oriented watches… that’s half a century of know-how that has been infused in the watch that we’re reviewing today, the Seiko Prospex Marinemaster 1000m Automatic Diver SBDX014 a.k.a the “Emperor Tuna”.

Seiko Prospex Marinemaster 1000m Emperor Tuna Rose Gold SBDX014

This watch is a beast, a purpose-built tool with no concessions, a watch with a singular objective: being a performing dive watch. If you are a guy wearing suits all week long, or if you feel comfortable being in a tuxedo, you might not be looking at the right page. However, if you are the kind of guy who’s into adventures, and if your wetsuit is a good friend of yours – or simply if you have the itch for a true dive watch – you’ll better continue reading, as this Seiko Prospex Marinemaster 1000m is far from being a second-grade option – even next to the most iconic and historically important dive watches.

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Background – Seiko Divers and the Tuna

For Seiko, everything related to diving started back in 1965, with the creation of the 62Mas, the first professionally-oriented dive watch from the Japanese manufacture. This watch has to be considered a milestone and as a historically important piece, as it defined many standards later used by Seiko, and by the entire watch industry – note that this very watch has been reissued in a modern version this year, with the highly coveted SLA017. This watch, known under the reference 6217 or 62Mas, featured a robust case, a 150m water resistance, a rotating bezel and a dial with specific markers and hands, which are now used by most of the dive watches created by Seiko. This watch also created the “Professional” collection by Seiko, which is now known as Prospex (for Professional Specifications).

An example of vintage Seiko 6159 “Tuna” – photo courtesy of FratelloWatches

In 1975 Seiko unveiled the Professional 600m diver’s watch (6159-7010). This is an important watch as it was the first titanium dive watch – a material that was more or less reserved for prototypes or NASA watches at that time, but a material with a lower density and a great resistance to corrosion, two important factors for pro-divers. It was also the first Seiko (and the first watch) to come with accordion-style strap – created because at high-pressures, the diving suits tend to shrink, so the rubber strap can be worn tightly to compensate for this fact. This anti-magnetic, highly shockproof, high-frequency (with 5Hz automatic movement) and highly luminous watch was also coming with a brand-new case architecture. Protected around by a black coated titanium outer case, the main part is made of a single bloc that is first highly waterproof (water resistant to 600m) but also a structure which is effectively impermeable to helium, thus eliminating the need for a helium valve. The watch could then be safely used for saturation diving to great depths. And this specific architecture gave the nickname “Tuna Can” to the watch. You can read more about the “The history of the Seiko Tuna” in this dedicated, in-depth article.

Seiko Golden Tuna Quartz 7549-7009 - 2

A Seiko “Golden Tuna” ref. 7549-7009

After three years of production, Seiko introduced the first quartz powered Tuna (ref. 7549-7009) which had a nitride plated titanium case and a titanium powder-coated shroud in order to minimize scratches during hard use. This material (nitride plated titanium) had a characteristic gold tint – a watch that Seiko aficionados named later the Golden Tuna. This Seiko Golden Tuna ref. 7549-7009 was a little smaller at 48mm but continued to have the character and design of its automatic sibling. In early 1986, Seiko introduced the ref. SBDS018 (or ref. 7C46-7009), with an increased water-resistance, now at 1000m. The movement was also upgraded to the 7C46, with a 5-year battery change interval – a movement that is still used in actual Seiko Tunas.

Seiko Darth Tuna SBBN013 Prospex - case

Seiko Prospex Darth Tuna SBBN013

The final step in the history of the Seiko Tuna is named the Prospex Darth Tuna SBBN013 – a watch that was fully reviewed on MONOCHROME, here. This watch is the modern descendant of the 40 years old Tuna ref. 6159-7010. At the time, it featured all the innovations that the brand injected into the collection, including a (high-end) quartz movement, for improved resistance and accuracy. Just like its ancestor, the Prospex Marinemaster 1000m “Darth Tuna” was big, protected and made to last – diameter of 48mm, its height is 15,3mm and a weigh of only 114g, thanks to titanium.

The preceding background/history was necessary, in order to understand where the Seiko Prospex Marinemaster 1000m Automatic Diver SBDX014 comes from, and what were the inspirations behind its design. Let’s now look at it.

The Seiko Prospex Marinemaster 1000m Automatic Diver SBDX014

Seiko Prospex Marinemaster 1000m Emperor Tuna Rose Gold SBDX014

The Seiko Prospex Marinemaster 1000m Automatic Diver SBDX014 was launched to celebrate 50 years of dive watches at Seiko, back in 2015. In short, it is a compendium of various historical “Tuna” pieces: the automatic movement just like the 6159, the golden parts like the 7549-7009, the 1000m water resistance like the SBDS018 and the Darth Tuna. Everything in this watch will be familiar to those in the know, which is exactly why it has been created. It is a tribute to the “Tuna” and, after all, an efficient dive watch with professional blood in its veins.

  • The Case and Strap

As surprising as it might be, this Marinemaster 1000m SBDX014 is a vintage-oriented piece. Yet, it admittedly doesn’t feel like most of the vintage-inspired dive watches, with this small and retro look of the 1960s. Indeed, the heritage of this watch is fully professional and far from being driven by anything else than performance. However, it has everything of a Seiko Tuna in its design and conception – and by that we mean the style of both the first Tuna 600m and of the Golden Tuna, both for the shape, the construction and the materials.

Seiko Prospex Marinemaster 1000m Emperor Tuna Rose Gold SBDX014

The Marinemaster 1000m SBDX014 is all about resistance, performance and reliability. Don’t look for elegance, discretion or daily-practicality. This is not the goal of this watch. It truly is a professional piece, made to last, made to perform, made to be an instrument for divers. No concessions have been made here, which is immediately felt when looking at and handling the watch. Just like its ancestors, the SBDX014 has a two-layer case, with a protective outer shroud. The central container – which holds the movement, the dial, the crystal and the bezel – is made out of titanium, as it has always been the case for Tuna watches. The case is also still relying on the one-piece/monobloc case structure, meaning that there is no screwed caseback. The movement is cased from the top, before the dial and the crystal. This allows for a 1,000m water resistance, even though some tests with a Darth Tuna attached outside an unmanned bathyscaphe proved a water resistance of no less than 3,284 meters…

Seiko Prospex Marinemaster 1000m Emperor Tuna Rose Gold SBDX014

In addition to this titanium central container, the Seiko Prospex Marinemaster 1000m “Emperor Tuna” features a distinctive outer-shell or “shroud” made to protect the case from shocks and to prevent any unintentional rotation of the bezel. As a concession to modernity, this protective device is now made out of highly resistant black ceramic instead of black-coated titanium – which makes it virtually impossible to scratch. The bezel insert, with 60-minute diving scale, is also made of the same material. The bezel, with 120 clicks, is pleasant to use and feels solid as a rock, just like the rest of the case.

The main attraction of this Marinemaster 1000m SBDX014 certainly is the use of rose gold plating on the visible metallic parts – bezel, screws and crown. Yet again, it is a tribute to an existing version, the Golden Tuna 7549-7009, however here this colour is purely decorative and doesn’t result from the nitride treatment applied to the material. This colour is, however, giving a unique appeal to the watch, which becomes less cold and technical than the Darth Tuna, and gains a bit in style. Still, this doesn’t hide the massive size of the case, which measures a whopping 48.2mm, combined with an also considerable 17.2mm in height. Quite a big baby on the wrist, yet this is explained by the very idea of a professional tool.

Seiko Prospex Marinemaster 1000m Emperor Tuna Rose Gold SBDX014

The Marinemaster 1000m SBDX014 is secured to the wrist by another iconic feature, the accordion-style strap, presented here in a soft and comfortable black silicone material. As with the rest of the watch, it doesn’t make many concessions to elegance and it is sized in order to be worn over a wetsuit – meaning, it is very long. Then again, a deliberate technical choice.

  • The dial and hands

Seiko Prospex Marinemaster 1000m Emperor Tuna Rose Gold SBDX014

The dial and the hands of the Seiko Prospex Marinemaster 1000m Automatic Diver SBDX014 are in the same vein as the rest of the watch: made to perform, yet with historical relevance and retro-flair. The dial combines a matte black plate, which avoids reflections, with large and contrasting indexes, all highly luminous and easily recognizable. Indeed, it uses a combination of dots, oval plots (at 3, 6 and 9) and triangle (at 12) to help quickly read the time in the dark. The hands follow the same idea, being large and generously filled with luminous paint. As a respectable diver, the minute hand is easy to differentiate from the hour hand, allowing for easy calculations (to calculate decompression steps or to time diving sessions).

Seiko Prospex Marinemaster 1000m Emperor Tuna Rose Gold SBDX014

The hands and the dial match the case in terms of colours and finishes, as both are rose gold plated or feature rose gold accents. Again, this brings a warmer and slightly original look to this watch, without compromising on legibility matters. The presence of the date remains, as usual with such watches, questionable yet historically relevant, as most Seiko divers, including the first Tuna and the 62Mas, featured date windows. At least here, we can notice a discreet integration, with a black disc matching with the dial.

  • The Mechanics

Inside the Seiko Marinemaster 1000m Emperor Tuna SBDX014 ticks one of the company’s middle range self-winding movements – the high-end ones are those created for Grand Seiko or the ones with a high-beat frequency. Yet here, this calibre has some noble roots, as it derived from a Grand Seiko movement, the Calibre 9S55. It has been used for quite some time now in other MarineMaster watches, such as the MM300. The main difference with the version that equips Grand Seiko watches is about decoration and adjustments (the 9S55 is regulated within +5 to -3 seconds per day).

The Calibre 8L35 is a modern movement that, as usual with Seiko, is developed, designed, manufactured and assembled fully in-house, at the Shizuku-ishi Watch Studio. It might not be finished with Haute Horlogerie standards (don’t expect polished bevelled angles or Geneva Stripes, we’re talking tool watches here), but it is, however, a reliable and efficient movement that prove its qualities. It ticks at 28.800vph / 4Hz, has 26 jewels and boasts approximately 50 hours of power reserve. This automatic calibre 8L35 is regulated to an average +15 / -10 seconds per day.

  • On the Wrist

Seiko Prospex Marinemaster 1000m Emperor Tuna Rose Gold SBDX014

You would expect this Seiko Prospex Marinemaster 1000m Automatic Diver SBDX014 to be a monster on the wrist, to be heavy and impossible to wear anywhere else than over a wetsuit… This is not entirely wrong, yet it must be nuanced. Of course,  with a diameter of more than 48mm and a thickness of 17mm, the Seiko MM1000 sits high and large on the wrist. It definitely makes a strong impact when worn. Furthermore, due to the integrated shape, it visually feels like a block simply “put on the wrist”, rather than strapped around the wrist.

Yet, due to this integrated construction, with the rubber strap attached under the watch and not between lugs, this watch is much more comfortable than one would expect. Even if the weight is distributed mainly on the head of the watch, it never feels wobbly – as long as you strap it on tight enough. One thing that needs to be taken into account when wearing it though: it is large and heavy, and you’ll have to be careful not to bump it on a wall or through a doorway. The good point is that the case is well protected.

Seiko Prospex Marinemaster 1000m Emperor Tuna Rose Gold SBDX014

Jokes apart, this is a watch that really requires a strong passion for tool-ish dive watches to be worn, otherwise, all of its specificities (the size, the protective shroud, the accordion-style strap) won’t become iconic features anymore but annoyances. As a true instrument, no concessions have been made, which also participates to the intact beauty of this watch.

  • Conclusion

No need to explain anymore, this Seiko Prospex Marinemaster 1000m Automatic Diver SBDX014 really is a passionate’s time-instrument, made with no concessions to aesthetics or elegance. It is a diving tool in its purest form, which is exactly why it is so desirable. It certainly won’t be the average Joe’s watch, however, for those who really are into iconic and professionally-oriented watches, this is a true grail.

Seiko Prospex Marinemaster 1000m Emperor Tuna Rose Gold SBDX014

In addition to that, the execution is faultless. Everywhere you’ll look, the watch is solid, precisely adjusted, and made with highly resistant materials that have been chosen not only for design purposes but because of their intrinsic properties. This is again the true definition of a professional dive watch, here with just the extra-coolness of the colour codes – black and rose gold. Yes, even instruments can be a bit fancy. The price is rather high at EUR 3,450 but totally justified by the overall package offered by this piece. More details on

Technical Specifications – Seiko Prospex Marinemaster 1000m Automatic Diver SBDX014

  • Case: Diameter 48.2mm x Thickness: 17.2mm – titanium monoblock case with protective shell in ceramic – Sapphire crystal – 1,000m water resistant – weight 158g
  • Movement: Calibre 8L35, in-house – self-winding – 50h power reserve – 4Hz frequency – 26 jewels – accuracy -10 to +15 seconds per day – Magnetic resistance 4,800 A/m – hours, minutes, seconds, date
  • Strap: Extra-strength silicone strap (210mm long) with titanium pin buckle
  • Reference: SBDX014
  • Price: EUR 3,450

8 responses

  1. Awesome looking watch. I keep drooling over the latest Grand Seiko’s. This is arguably the coolest dive watch out there. I don’t need a dive watch, but if Seiko needs a long term GS tester I’m their man.

  2. Hi Brice,
    thanks for your comprehensive article. This is indeed the most iconic toolwatch ever (maybe with the ProlProf), no compromises and pure functionality.
    In an age where most claim to be what they’re not, it is a pleasure to see substantial pieces like this.


  3. I’ve had mine since May and it is an amazing watch. Everything about it says quality and function as a true tool watch. Highly recommend one.

  4. This is all well, but any professional Scuba diver has a dive computer, not a watch.
    A dive computer has all the information you want under water. A scuba diver is not interested in the actual time while diving……. So to wear a real good waterproof watch on a boat makes sense, not when you are under a boat.

  5. rene bense, vamos ver,,, si buceas con un reloj es porque te gustan relojes, no los ordenadors de buceo que los odio,,, soy instructor de buceo y jamas bajo soin un reloj o incluso dos, mas el ordenador si,,, pero con tu comentario, deduzco dos cosas

    no te gustan los relojes o no tienes dinero para comprarlo dices cualquier cosa para autojustificarte

  6. What? You don’t wear a watch and a dive computer? You mean you want to put your life in the hands of a single piece of equipment? I mean I always have a spare wheel on my car, why would I not have a dive watch and a dive computer just in case?

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