Seiko Marinemaster: All About Seiko’s Outstanding Diver

One of the world’s largest and most renowned watchmakers is the Japanese brand Seiko. The brand offers a wide range of outstanding watch models, including professional dive watches that are loved by watch enthusiasts worldwide. On top of that, Seiko is also known globally for its introduction of the quartz movement in the sphere of horology. Thanks to its ceaseless innovation and consistent production of high-quality watches, many watch aficionados have developed an inclination toward the brand’s products over the years. 

Of all the dive watches in Seiko’s catalog, one particular standout is the Seiko Marinemaster. Powerful and robust, the Seiko Marinemaster is a distinctive timepiece that has carved out its own place in the brand’s history. Without further ado, let us get better acquainted with the Seiko Marinemaster, its history, achievements, and the best Marinemaster models that money can buy you. 

Seiko Marinemaster: A Brief History

First released in 1968, the Seiko Marinemaster has been around for a very long time, with many new Marinemaster models being released over the years. Because of the extensiveness of its history, we will only be discussing a few of the Marinemaster’s significant milestones, particularly those that relate to the models we will be discussing in greater detail later in this article: 

1968: Seiko releases its first Hi-Beat dive watch, the Marinemaster. Launched just three years after Seiko first ventured into the dive watch market, the 1968 Marinemaster Ref. 6159-7001 showed off a monobloc case and an impressive 300-meter water resistance capacity. The high-beat frequency of this Marinemaster’s new, built-in driving system also ensured exceptionally precise timekeeping, even when used underwater. 

1975: The first Seiko “Tuna” Marinemaster Ref. 6159-7010 was born. It came in a chunky yet lightweight titanium build and was made especially for professional diving. This Seiko Marinemaster model had an outstanding 600-meter depth rating and its outer case was bolstered by a thick shroud which provided additional protection from scratches and impacts. 

1978: Three years later, an upgraded timepiece with a similar build to the 1975 Seiko “Tuna” Marinemaster Ref. 6159-7010 was released. This new Marinemaster was the first saturation diving watch ever to utilize an in-house quartz movement. It continues to epitomize Seiko’s dedication to never-ending innovation. 

2005: Fast forward to thirty years later, and the Marinemaster Spring Drive Ref. Ref. SBDB001 was introduced. This watch was crafted using lightweight titanium and equipped with a luxurious sapphire crystal, which served to protect the watch’s dial. This watch was well-suited for saturation diving with its water resistance capacity of 600 meters.

Today, the Seiko Marinemaster sub-collection has expanded to hold a wide variety of timepieces, all of which fall under the extensive Seiko Prospex series. These, of course, include the “Tuna” Marinemaster models. Fun fact: the “Tuna” nickname awarded to these timepieces is a witty reference to the cylindrical shape of a tuna can. The Seiko “Tuna” Marinemaster watches showcase round, shrouded cases that are said to resemble actual tuna cans, hence the nickname. This tuna can design continues to be used in modern Marinemaster models today. 

In addition, there are two distinct features that tie every Marinemaster watch together. The first is an aesthetic one: the off-center placement of the Marinemaster’s huge crown on the right side of the case, at 4 o’clock. Secondly, each Marinemaster variant also possesses an excellent water resistance capacity that exceeds 200 meters. 

Now that we are more familiar with the collection as a whole, let us take a look at some of the best Marinemaster models on the market. 

Best Seiko Marinemaster Models

1. Seiko Prospex Marinemaster Ref. SBBN035

Front View of Seiko Prospex Marinemaster Ref. SBBN035

First on this list is the Seiko Prospex Marinemaster Ref. SBBN035, which is also famously known as the “Ninja Tuna.” The striking all-black theme is what this timepiece is all about. This watch comes in a bulky 47.7mm case made of stainless steel. Not only is the case wide, but it is also quite thick, with a height of 14.7mm. This gives the Ninja Tuna a nice, substantial heft on your wrist. The black-tone case is coupled with a matching black silicone bracelet which is durable enough to carry the weight of the timepiece. 

As per its all-black theme, the dial of this watch also comes in matte black. It has a fairly simple layout, with geometric hour markers and broad arrow-head hands, all of which are generously coated with lume. A day-date window is also located next to the 3 o’clock marker. Placed atop the case is an 120-click rotating bezel with a black insert for its elapsed time scale. 

The Ninja Tuna is driven by a Seiko 7C46 quartz movement. Held together by seven jewels, this movement has an excellent battery life of five years. On top of that, the Ninja Tuna also has a respectable depth rating of 300 meters. 

If you want a tough yet subtle-looking dive watch, you can get the Seiko Prospex Marinemaster Ninja Tuna Ref. SBBN035 for $1,149 USD.

2. Seiko Prospex Diver Marinemaster Ref. SBDX017

Front View of Seiko Prospex Diver Marinemaster Ref. SBDX017

Next on this list is the Seiko Prospex Diver Marinemaster Ref. SBDX017. This Seiko Marinemaster watch is packed in a 44.3mm stainless steel case, along with a three-link case made of the same material. Both the case and bracelet are treated with Seiko’s unique Diashield coating. This enhances their resistance to scratches and protects the elegant, brushed mirror finish of the watch’s exterior. 

The watch’s gear-edged elapsed time scale bezel and dial, on the other hand, come in jet-black. The dial is adorned with geometric hour indices and thick sword hands, all of which are coated in the brand’s patented LumiBrite material, allowing for optimal legibility even in the dark. A small date display, outlined in silver, also sits at 3 o’clock. 

Driving this Seiko Marinemaster piece is the brand’s in-house 8L35 automatic movement. Based on the Grand Seiko 9S55 caliber, this movement has a solid 50-hour power reserve. The Seiko Prospex Diver Marinemaster Ref. SBDX017 is also able to withstand water pressures of up to 300 meters. 

This luxurious Seiko Marinemaster watch sells at around $2,999 USD.

3. Seiko Prospex Marinemaster Ref. SLA021J1

Front View of Seiko Prospex Marinemaster Ref. SLA021J1

In this entry, we have what is perhaps the most popular Marinemaster model ever: the Seiko Prospex Marinemaster Ref. SLA021J1. This watch is presented in a 44.3mm stainless steel case with a bracelet made of the same material. The 15.4mm width of the case makes this watch thicker than the average dive watch. 

As with the previous Marinemaster models, this watch shows off a stark black dial. It is furnished with LumiBrite-coated geometric indices, satin-finished hands, and a date complication at 3 o’clock. The yellow seconds hand also stands out clearly with its lovely, bright yellow tone, which adds a burst of vibrancy to this monochrome watch face. 

This watch runs on the Seiko 8L35 automatic movement. Aside from having a reliable 50-hour power supply, it also has a depth rating of 300 meters. 

This powerful Seiko Marinemaster classic is priced at approximately $2,399 USD.

 4. Seiko Prospex Ref. SPB077J1 

Front View of Seiko Prospex Ref. SPB077J1

The next timepiece on this list is the Seiko Prospex Marinemaster Ref. SPB077J1. More commonly known as the Seiko Baby Marinemaster, this is a modern re-interpretation of Seiko’s 1968 Marinemaster 300m dive watch. It is housed in a 44mm stainless steel case that measures 13.1mm thick, making it relatively smaller and slimmer compared to other Seiko Marinemaster models. This is coupled with a sleek three-link stainless steel bracelet and a black elapsed time scale bezel. 

Complementing the bezel is a matte black dial. This dial follows a straightforward design, comprising circular and trapezoidal hour indices, thick arrow-headed hands, and a compact date aperture at 3 o’clock. The hands and indices are all treated with Seiko’s LumiBrite material for optimal legibility at all times. 

Underneath this simple watch face, you can find the brand’s in-house 6R15 automatic movement. This caliber possesses a 50-hour power supply and is equipped with hand-winding and hacking capabilities. Finally, as a “baby” version of the Seiko Marinemaster, this dive watch comes with a depth rating of just 200 meters. 

The Seiko Prospex SPB077J1 costs $1,595 USD. It is a great choice for those seeking a more budget-friendly Seiko Marinemaster option. 

5. Seiko Prospex Marinemaster Spring Drive Ref. SBDB011

Front View of Seiko Prospex Marinemaster Spring Drive Ref. SBDB011

Next up, we have the Seiko Prospex Marinemaster Spring Drive Ref. SBDB011. This watch comes in a robust titanium case measuring 46mm wide and 17mm thick, along with a bracelet made of the same material. Despite its large size, however, the watch’s titanium construction makes it quite lightweight compared to other stainless steel watches. 

Standing out against the watch’s all-silver exterior is a black elapsed time scale bezel and a matching black dial. This dial has a slightly more complicated layout compared to the aforementioned Seiko Marinemaster models. It consists of LumiBrite-coated hour indices in various geometric shapes, broad sword hands, a date window at 3 o’clock. An arcing power reserve indicator is also located near the 9 o’clock marker. 

This watch is powered by an in-house Seiko 5R66 movement. As an automatic movement, this caliber provides an extended power reserve of 72 hours. It also possesses an impressive depth rating of 600 meters, so you can easily use this watch for deep-sea saturation diving. 

With its lightweight build and powerful movement, the Seiko Prospex Marinemaster Spring Drive Ref. SBDB011 is definitely a great pick. The price of this watch costs $3,699 USD.

6. Seiko Prospex Marinemaster Ref. SBDX014 

Front View of Seiko Prospex Marinemaster Ref. SBDX014

The next watch on this list is the Seiko Marinemaster Ref. SBDX014, which is more commonly known as the “Emperor Tuna.” As befitting its name, this watch is encased in a majestic 48.2mm titanium case. Adding to its already massive size is the black ceramic shroud that surrounds the watch, giving it its robust “tuna can” shape. Despite its large build, however, the Emperor Tuna is actually quite light, thanks to its lightweight titanium case construction and sturdy black silicone bracelet. 

The dazzling contrast between the black and rose gold hues of this watch is easily one of its most fascinating features. The lovely rose gold accents on the Emperor Tuna’s bezel and crown truly help make it distinct from its Marinemaster peers. This effect is enhanced by the watch’s geometric, LumiBrite-coated indices and rose gold-tone arrow hands, which stand out cleanly against the dial’s black finish. A tiny date display can also be found between the 4 and 5 o’clock markers. 

Inside this luxurious-looking timepiece, you can find an in-house Seiko 8L35 movement, which possesses a reliable 50-hour power supply. In addition, the Emperor Tuna is also able to withstand water pressures of up to 1000 meters, which is excellent for saturation diving. 

Priced at $3,149 USD, this one-of-a-kind Seiko Marinemaster watch is a must-have for any dive watch collector.

7. Seiko Prospex Marinemaster Ref. SBEX005

Front View of Seiko Prospex Marinemaster Ref. SBEX005

Joining this list is the Seiko Marinemaster Ref. SBEX005, which stands out with its stylish silver-and-blue colourway. This watch utilizes a chunky 48.2mm titanium case which measures 19.77mm thick and a bracelet made of the same material. While its oversized case gives this watch a considerable presence on your wrist, its lightweight titanium build ensures that it is not too heavy to tote around. Fixed atop the case is a titanium bezel with a metallic blue elapsed time scale insert and a diagonal-cut design that adds more personality to this stylish watch. 

Another highlight of this Seiko Marinemaster watch is its lovely blue dial, which showcases an alluring, ocean-inspired wave texture. This dial is beautifully contrasted by satin-finished sword hands and LumiBrite-covered geometric indices. A small date aperture can also be found between the 4 and 5 o’clock markers.

Driving this watch is an in-house Seiko 8L55 automatic movement. Held together by 37 jewels, this calibre can last for up to 55 hours when fully wound. Like the Seiko “Emperor Tuna” Marinemaster, this watch also has an excellent depth rating of 1000 meters. 

The Seiko Prospex Marinemaster Ref. SBEX005 is worth approximately $5,089 USD, making this one of the more expensive Seiko Marinemaster pieces available. 

8. Seiko Prospex Marinemaster Hi-Beat Ref. SLA025

Front View of Seiko Prospex Marinemaster Hi-Beat Ref. SLA025
Image by: eBay

Eighth on the list is the limited-edition Seiko Prospex Marinemaster Hi Beat Ref. SLA025. As a homage to the 1968 Seiko Hi-Beat, this is a modern take on the aforementioned vintage dive watch. It uses a 44.7mm monobloc stainless steel case and a pyramid silicone strap in black. On top of the case, you can find a 120-click unidirectional bezel. This bezel is fitted with a black ceramic insert, bearing exquisite gold indicators for its elapsed time scale. 

Like many other Marinemaster models, this watch also showcases a simple black dial. However, this watch distinguishes itself with the luxurious gold accents peppered across the dial. The dial’s luminous geometric indices and sword-shaped hands are all encased in gold plating, while the date complication at 3 o’clock is also framed in gold.

This Marinemaster piece runs on the brand’s in-house 8L55 automatic caliber. This gives the watch a 55-hour power supply and a reliable depth rating of 300 meters. 

As a limited-edition gem, there are only 1,500 pieces of the Seiko Prospex Marinemaster Hi Beat Ref. SLA025 available in the world. It retails at around $4,900 USD.

9. Seiko Prospex Ref. SBDX043

Front View of Seiko Prospex Ref. SBDX043
Image by: Seiko Watches

For the next watch, we have another limited edition timepiece, the Seiko Prospex Marinemaster Ref. SBDX043. Released in honor of the brand’s 140th anniversary, this Marinemaster model is one of three limited-edition divers launched by Seiko under the branding of “Iriomote Island.” It is housed in a 44.3mm polished stainless steel case and a matching stainless steel bracelet. Fixed on top of the case is a black elapsed time scale bezel, with ridged edges that provide wearers with a better grip. 

The star of this watch, without a doubt, is its mesmerizing green dial. Boasting a rich green hue, this dial contains geometric hour indices and satin-finished hands that are filled with LumiBrite, maximizing legibility in the dark. Its seconds hand comes in a distinctive, bright yellow hue, adding a hint of vibrancy to this dark watch face. You can also find a compact date window located at 3 o’clock as well. 

Like many other Seiko Marinemaster models, this timepiece is powered by the brand’s in-house Seiko 8L35 automatic movement. Aside from possessing a 50-hour power supply, this watch also has a solid 300-meter depth rating. 

Seiko produced only 3,000 pieces of the Seiko Prospex Ref. SBDX043. Thanks to its exclusivity and its charming design, this Marinemaster model sells at $2,509 USD.

10. Seiko Prospex Marinemaster Ref. SBBN027

Front View of Seiko Prospex Marinemaster Ref. SBBN027

For the last watch in this list, we have the Seiko Prospex Marinemaster Ref. SBBN027, popularly known as the “Yellow Tuna”. This watch is presented in a colossal 49.3mm black-tone case and a robust silicone strap in black. Surrounding the case is a glossy black shroud made of ceramic which adds to the watch’s heft and protects it from any impacts or scratches. You do not have to worry about the Yellow Tuna’s large size, however, as it is actually quite light and comfortable to wear — thanks to its titanium build. 

On top of the watch’s case, you can find a 120-click unidirectional bezel with a funky yellow insert for the elapsed time scale. This vibrant bezel helps give the watch a certain lively personality. Yellow accents can also be found scattered all over the watch’s black dial, in particular, on its minute and seconds hands, further enhancing the watch’s quirky vibe. Aside from that, this dial is also decorated with geometric hour markers in white, an arrow-headed hour hand, and a day-date display at 3 o’clock. 

Driving all of these functions is the brand’s in-house Seiko 7C46 movement. This automatic movement carries a power reserve of about 50-hours. This is complemented by the watch’s incredible 1000-meter depth rating, which makes it well-equipped for long-distance saturation diving. 

If you want a powerful yet fun dive watch, you can buy the Seiko Prospex Marinemaster Ref. SBBN027 for approximately $2,049 USD.

Final Thoughts

The Seiko Marinemaster models are indeed amazing and innovative timepieces that have helped exhibit the excellence of Seiko’s craftsmanship over generations. Without a doubt, these Marinemaster pieces are a great inclusion to one’s growing dive watch collection. With their robust movements and impressive water-resistance capacities, you would definitely not want to miss out on these Seiko Marinemaster watches. 

All images courtesy of WatchShopping website, unless otherwise stated. Photo Credits: eBay and Seiko Watches. Featured image courtesy of ludalmg90 on Flickr.

Are you interested in military-inspired digital watches? Check out our review of the Nixon Regulus.

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