Seiko Marinemaster: Full Guide with the BEST References (2024)
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Seiko Marinemaster

Seiko Marinemaster: Full Guide with the BEST References (2024)

Seiko is a familiar brand name to watch enthusiasts and is much loved for its reliability, rich history, and versatility. Buying a Seiko watch means being a part of a community that knows quality when they see it. One of Seiko’s biggest selling points is its seemingly endless catalog of fantastic watches that can impress even the most dedicated critic.

The brand is highly collectible, and owners might start with one of Seiko’s many fantastic and robust dive watches before diving into more of their collections, like their dress and field watches. Seiko’s dive watches, in particular, are held in high regard, with many sporting nicknames affectionately given to them by enthusiastic fans, such as “Samurai” and “Tuna.”

One dive watch line that Seiko offers is the legendary Marinemaster collection. Many watches are a part of this collection, and taking the leap to buy one may be a challenging experience. We’re here today to provide you with a look into the storied history of the legendary dive watches that professional divers trust to help them explore the fierce ocean waters and a guide that highlights some of the many references in the Marinemaster collection.

What is the Seiko Marinemaster?

As the name implies, the Seiko Marinemaster is a watch born to be in the water and survive in the murky and mysterious depths of the ocean. It is a watch that will faithfully serve its purpose with excellent reliability. The Marinemaster line falls under the extensive Prospex collection of Seiko watches.

Prospex, short for “professional specifications,” is Seiko’s answer to the rigorous demands of professional diving and exploration. Many watches under the Prospex line can be considered a Marinemaster. Since the release of the first Marinemaster, Seiko has expanded this line with several different timepieces. However, it is important to note that some are not explicitly labeled as Marinemaster.

Generally, the Marinemaster line consists of watches with very high depth ratings of over 200 meters of water resistance, a crown located at the 4 o’clock position, and is classified under the Prospex range. Following this general rule makes identifying a member of the Marinemaster family a simple and painless process.

Seiko Marinemaster History

The 1960s was a tumultuous era of social upheaval that included major wars and periods of social unrest. In the world of diving, however, the 1960s is when exploration and diving achieved some of its greatest innovations and changes.

Right at the start of the decade, two intrepid explorers named Jacques Piccard and Don Walsh made history as the first people to reach the bottom of the Challenger Deep, the deepest known point in the ocean. They did so on their submersible vessel, the Trieste. This momentous event set the tone for the rest of the decade and made exploring one of the Earth’s final frontiers an exciting adventure for the brave and curious.

During this period, watches were prized as reliable workhorses instead of status symbols. They were expected to perform and keep their wearer safe because diving was a demanding profession. Divers who spend too long underwater risked endangering their life or suffering from physiological conditions like the bends.

There was a great need for accurate timepieces that could survive the oceans with their wearer and accompany them as they descended into the waters below. For the Swiss watchmaking industry, they answered with offerings from respected brands like Rolex, Omega, and Blancpain. On the other side of the world, the Japanese watchmaking industry needed to respond in turn.

Seiko answered that call in 1965 with the extremely robust Seiko 6217-8001/62MAS. This watch is the earliest ancestor of the Marinemaster. The 6217-8001 started the Seiko trend of creating timepieces that would keep divers alive in depths that would make most people shiver thinking about it.

This watch was designed to be functional at up to 150 meters underwater. Although it was only produced for a few years, its importance cannot be understated, as it is Seiko’s first serious professional dive watch and attempt to challenge Swiss watchmakers.

Two years after the 6217-8001, Seiko followed that up with the 6215-7000. The water resistance doubled from 150 meters to a staggering 300 meters. This watch featured the crown at the 4 o’clock position, a feature that continues to be seen in nearly every member of the modern Marinemaster family.

In addition to being an interesting conversation starter, the 4 o’clock crown serves a practical purpose. It provides easier access to the crown instead of the usual 3 o’clock position, especially when diving. In the perilous situations that divers can find themselves in, any advantage or comfort the equipment can offer is much appreciated.

Seiko continued its success with the release of the 6159-7001, which looked extremely similar to its predecessor but featured an interesting hi-beat movement that offered extreme precision and accuracy. In the 1990s, Seiko released the now hard-to-find SBCN005, a quartz-powered titanium watch that is the predecessor of the much more famous SBDX001.

Much later on, in the year 2000, Seiko released the Marinemaster 300 SBDX001 to a delighted Japanese exclusive market. Despite its success in the Japanese market, Seiko was slow to release Marinemasters outside of Japan. However, now that Seiko has released more Marinemaster models into the global market, everyone can get their hands on one of these coveted pieces.

Is the Seiko Marinemaster worth buying?

The Seiko Marinemaster 300 appeals to a wide range of people, ranging from professional divers to casual collectors. Its handsome looks, rich history, practicality, and accuracy are sure to delight anyone who has the chance to see a Marinemaster for themselves.

Undoubtedly, the Marinemaster 300 holds a special place in history as one of Seiko’s best contributions to the world of diving. Collectors will appreciate the historic nature of the watch while casual wearers will enjoy its rugged appearance with a touch of luxury mixed in. This classically designed tool watch fulfills its duties as a professional diving companion and looks good while doing it. The case is expertly finished, and the piece is comfortable to wear.

Marinemasters, at minimum, boast a water resistance of 200 meters, with many having 300 meters. Such watches will be perfect for water activities, ranging from a dip in the pool to coral reef snorkeling. The Marinemaster is also more than prepared for any adventures on land, with a tough stainless steel construction that will last a lifetime.

The time will be pinpoint accurate, with Seiko’s marvelous mechanical movements providing accuracy that matches and exceeds certified chronometers. Finally, Marinemasters feature a highly legible dial that makes telling the time easy with just a glance. The bold markers, generous lume, and large font contribute to this ease.

Every watch has its cons, and the Seiko Marinemaster 300 is no exception. Achieving the behemoth 300 meters of water resistance comes with a cost. The case is thick, with most Marinemasters being around 15 mm thick. Therefore, the watch sits tall on the wrist, which may bother some people who want a more sleek and understated timepiece.

Potential buyers can also consider other lesser known watches at the Marinemaster’s price point. The range varies, but other Swiss-made divers are also available at these prices. Marinemaster buyers will be lovers of Japanese watches, enthusiasts, and anyone looking for a large, rugged, practical watch that can handle any situation. The Marinemaster is a hefty piece, and anyone who is able to put one on their wrist will feel the weight. Wearers will definitely be aware of the watch’s presence.

The Best Seiko Marinemaster References

Many watches are in the Marinemaster line, but this guide will list several references in chronological order. If the word “Marinemaster” is on the watch, it will either be on the face of the watch, the caseback, or the tag that comes with the watch.

Seiko SBCN005

Seiko SBCN005

Also called the Transocean, the SBCN005 is one of the most unique models in the Marinemaster lineup. The watch was released in the 1990s. It looks completely different from later models and does not even use a mechanical movement.

Instead, the SBCN005 was a lightweight, titanium watch powered by the Seiko 7k32 quartz movement. The watch features a gorgeous dark blue dial with streaks of striking yellow accenting various parts of the watch. The watch also had a barometer scale, second time zone, and sapphire crystal lens.

Seiko SBDX001

Seiko SBDX001

The SBDX001 is the watch most people will immediately think of when they hear the word “Marinemaster.” For many enthusiasts, this is the definitive Marinemaster. Released at the turn of the century in 2000, the SBDX001 was a Japanese domestic market (JDM) exclusive watch for many years and was difficult for global audiences to find.

Instead of using a quartz movement, Seiko opted for a robust 8L35 mechanical movement for this watch. The design of this watch echoes back to its early ancestors from the 1960s and has a slick black dial. Measuring at nearly 16 mm thick and 44 mm in diameter, the watch is not subtle. Additionally, the watch features a unidirectional bezel, lumed hands, and a screw-down crown.

Seiko SBDX003 & SBDX005

Seiko released a collection of seven watches in 2000 as a part of their Seiko Historical Collection. The collection featured dive watches, dress watches, quartz watches, and pocket watches. The SBDX003 and SBDX005 are both highly prized collector items.

They were limited edition releases of only 500 SBDX003s and 1,000 SBDX005s. The SBDX003 has gilded yellow indices and golden text on a deep black dial. The SBDX003 also only came on a rubber strap.

The SBDX005 is in the “Tuna” style of Seiko cases, named affectionately by fans because it resembles, appropriately enough, a can of tuna. Both watches did not have the word “Marinemaster” on them, unlike the SBDX001. However, given their extreme water resistance, they certainly are Marinemasters.

Seiko SBBN027

Seiko SBBN027

The SBBN027 is a massive watch housed in a Tuna-style case and features a vibrant yellow bezel that makes the watch stand out. The 2015 release “Yellow Tuna” is a fun addition to the Marinemaster family. The bright colors don’t compromise the build quality of the watch, however.

It is very much a serious dive watch, water resistant to a titanic depth of 1,000 meters. Despite its massive 49 mm case, this piece is not very heavy because of the titanium build. The silicone strap is expertly finished and is flexible and strong. A new SBBN027 is around $2,100.

Seiko SBDX017

Seiko SBDX017

Released in 2015, the SBDX017 is the successor to the SBDX001. They are nearly identical in design and even share the same 8L35 automatic movement, but the SBDX017 features several upgrades over the older model. Notably, the SBDX017 features Diashield coating on the bracelet, which protects the stainless steel from scratches.

The Diashield coating also gives the stainless steel a slightly darker color. The watch features upgraded lume compared to the original and a Seiko Prospex logo etched onto the crown, which is normally unsigned. The SBDX017 was discontinued by Seiko in 2018.

Seiko SBDX021/SLA019

Seiko SBDX021/SLA019

After the SBDX017’s discontinuation, the SBDX021 was the next successor to the Marinemaster name. Instead of the deep black dials that most Marinemasters have, the SBDX021 has a luscious, mossy green dial. The SBDX021 was a limited release of 1,968 pieces, referencing one of Seiko’s most important years for making watches. With an upgraded ceramic bezel, sapphire crystal lens, and reliable 8L35 movement, this watch was a treat for Seiko fans.

Seiko SLA025

Seiko SLA025

Many of Seiko’s releases reference older models, and the SLA025 is no different. The SLA025 was a limited release in 2018, with only 1,500 models available. Vintage-inspired watches are extremely popular, and the SLA025 closely resembles Seiko’s 1968 diver watch with modern upgrades. The SLA025 was so beloved and well-received that it was even named by the Grand Prix d’Horlogerie de Genève (GPHG) as the year’s best sports watch.

The GPHG is one of the world’s most prestigious watch organizations that recognizes the year’s best innovations and creations in the watch world. The SLA025 completely updates the movement and features the luxurious 8L55 high-beat movement, a movement that is a variant of a movement used by Seiko’s ultra-luxury line, Grand Seiko.

Seiko SPB077

Seiko SPB077

The intent for these watches is apparent with Seiko’s official full name for them: “Prospex 1968 Diver’s Modern Re-Interpretation.” This 2018 release watch is only a sample of the larger selection from Seiko. Interested buyers can choose from different colors and upgrades, but the watch itself maintains the spirit of Seiko’s dive watches from 1968 and transports it to the modern world. Like many of Seiko’s watches, the SPB077 and a few similar pieces have a nickname: the “Baby Marinemaster.”

The SPB077 features a classic black dial and slimmer dimensions than most other Marinemasters. The case diameter is 44 mm, and the thickness is 12.7 mm. The watch is powered by the 6R15 automatic movement, which is found in many other modern Seikos. As the “baby” in the family, the SPB077 has a respectable water resistance of 200 meters. A new SPB077 can be yours for around $1,050.

Seiko SBDX023/SLA021

Seiko SBDX023/SLA021

This handsome 2019 release from Seiko is one of the latest iterations of the modernized Marinemaster 300. The watch has numerous upgrades that make it even tougher and more resistant to any challenge the ocean can throw at it. Instead of an aluminum bezel, Seiko has opted for an extremely scratch-resistant ceramic bezel.

The bracelet has a flexible diver extension that makes wearing the watch even easier. The build quality is impeccable, and the timepiece is completely sealed shut, thanks to its sturdy monobloc case design. The 8l35 automatic movement powers the watch, another variant of a luxurious Grand Seiko movement. A new Seiko SBDX023/SLA021 is around $3,100.

Seiko SBDC167/SPB299

Seiko SBDC167/SPB299

One of the newest watches on the list, the SBDC167/SPB299, is a Marinemaster with a mesmerizing icy blue dial. This 2022 release is a part of the “Save the Ocean” special editions released by Seiko, commemorating Seiko’s dedication to protecting the world’s oceans.

New watches are constantly added to the “Save the Ocean” line, all of which feature an exciting special edition colorway. It is beautifully sized at 42 mm and is thinner than most other Marinemasters, with a case thickness of 12.5 mm. A new SBDC167/SPB299 is around $1,250.


The Seiko Marinemaster is an extensive collection that embodies Seiko’s dedication to creating excellent Japanese products that are built to last. Buyers will be able to enjoy the watch’s rich history and marvelous engineering. Marinemasters will be a fine addition to any collection and will easily be able to compete with watches much more expensive than it.

The practicality, legibility, accuracy, history, and construction of the Marinemaster makes it a staple in the Seiko catalog, and Marinemasters will continue to be on the wrists of eager wearers for a long time.

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