How many watch enthusiasts, I wonder, began their collecting journeys with lure of a Seiko diver? I imagine the number is high. Affordable, ubiquitous, and downright cool, these everyday carry legends have defined—and refined—the essence of a dive watch for more than half a century. Notably, Seiko was not among the early forerunners in this field. This honour belongs to the likes of Blancpain and Zodiac—a full decade earlier than the Japanese brand. But the Seiko dive watch story is an exhibition in slow and steady wins the race.
Few tool watches manage to achieve that heady space of voguish collectability, occupied by brands like Rolex and Omega, while remaining accessible to the common man. The sheer number of models, references, and price points—all products of function-first design, upholding and surpassing the ISO 6425 standards—mean that somewhere in the Seiko catalogue there is a dive watch waiting for you.
More than that, unlike many luxury brands, Seiko has built a continuum of dive watches throughout the years—from the beater to the upper end of refinement—which allow the collector to evolve and grow with the watchmaker. They have achieved this unique space through years of research and innovation. You don’t need to be diver to appreciate Seiko. The point is…you could be.
Let’s get started with a backroll into Seiko waters.
The 62MAS (1965)
Ask an untutored layman to draw you a dive watch and he will probably reproduce—to alarming similarity—the 62MAS. That’s how important the Diver’s 150M was to the development of dive watches. Much of what came after has simply been variations on a theme. Seiko’s official name for the watch was the 62 Seikomatic Calendar (Diver’s Watch). The 62MAS moniker is assumed to have originated from the first two digits of its reference number (6217-8000/1) and the term “autoMAtic Selfdater.” Nonetheless, it established, or reinforced, a number of the elements which would become touchstones of dive watch design. The original came in a 37mm tonneau-shaped case with squared off lugs and was water resistant to 150m. It sported a bi-directional bezel for calculating dive times, drilled lugs, easily legible luminous hours markers, and similarly lumed hands. It also had a distinctly large, unprotected crown. The 6217 automatic movement used in the watch, vibrated at a frequency of 18 000bph. While large for a watch of its era, the silhouette of the 62MAS would become the seminal shape for skin divers of its generation. And it remains much copied to this day.
The 62MAS was an express commission from the Japanese Antarctic Research Expedition to Seiko for its 8th expedition. However, their order arrived at a time when the brand was deep into the development of electronic measurement devices for the 1964 Tokyo Olympics. With little time or manpower to devote to the request, Mr. Taro Tanaka, head of development and chief engineer at Seiko in those years, drew inspiration from Swiss skin divers already in existence. As such, astonishingly, the original design of the 62MAS was accomplished within a month and went into production unpolished.
The 6217-8000 reference was only ever produced from April to May in 1965. It is known among collectors as the highly sought after “Small Crown” variant. It was the later 8001 series which would eventually equip the 8th Japanese Antarctic Expedition in 1966. Its larger crown was much easier to manipulate when wearing gloves.
Interestingly, despite its position as the progenitor of all Seiko divers, the 62MAS remained (until very recently) the only professional-grade dive watch where the brand placed the crown at the 3 o’clock position.
Of late, re-releases of the 62MAS abound. Among the more popular are the limited edition SLA017, the more accessible SPB051/53, and the much-vaunted SPB143, 145, 147, and 149 series.
Following the launch of the 62MAS, Seiko took a two-pronged approach to its new dive watch program. The development of its 6215/6159 series would be the flagship of its professional divers; whereas the 6105, 6306, and 6309 would mark a more accessible line of watches for recreational divers–a field that was entering its heyday in the mid 1960s, with developments like PADI certification in 1966.
The 6215-010 (1967)
Seiko pushed its own envelope two years later with the release of their first 300m diver. Other than the doubling of its water resistance, the new watch would establish the emblematic placement of the crown in the 4 o’clock position. But, of equal note, the new watch used a monobloc case and an upgraded 35-jewel, hackable movement with a fifteen-minute elapsed time bezel scale. The monobloc construction eliminated the need for a caseback and played a large role in the increased water resistance.
The 6159-7001 (1968)
Shortly after the release of the 6215-010, Seiko introduced its first hi-beat movement (10 vibrations per second). Based on the manually wound Grand Seiko calibre 6159A, the 36 000bph-movement meant increased accuracy for the Diver’s 300m. The monobloc case remained and it featured a screwed-down crown. The bezel was available both as a countdown and an elapsed time variant. Production of this watch was limited to a single year between 1968-1969.
As such, the watch is highly collectible today, and like the 62MAS, received its own limited edition re-issue in 2018, with the SLA021/23/25—lovingly dubbed the Marine Master. It is now available in slightly more accessible formats, like the SBDX and SBDC series—also called the Baby Marine Master.
The 1970s were a tumultuous time for the watch industry as a result of another Seiko development, the quartz movement. However, while this will certainly play a role in the brand’s (and other’s) dive watch program, the Seiko focus continued to be two-pronged during the decade, with the development of its much-mythologized Professional Diver series on the one hand, and the furtherance of their 150m divers by way of several iconic designs.
The Professional Diver’s 600m (1975)
In an occurrence that is almost legendary now, Seiko received a letter back in 1968 from Hiromi Oshima, a commercial diver operating out of Kure City in Japan. Commercial divers, unlike their recreational counterparts, often operate in saturation—living in pressurized chambers for days and weeks without resurfacing. According to the letter, the 300m divers being produced by the brand were not sufficient in this environment. Aside from damage inherent to the construction work being performed, helium gas penetration, present in the diver’s breathing mix, proved mortel to the timepieces. The gaskets in use allowed the gas to seep in and build up inside the watch. Over time, the accumulation created sufficient pressure to blow off the crystals.
Not long after the letter surfaced, representatives from the company responded by visiting the diver’s place of work–an oil platform. Tatsuro Akabane, from the design team of the Suwa factory, and Taro Tanaka (still head of development at Seiko) interviewed Oshima and his colleagues regarding their concerns. The men even descended in a diving bell to experience the conditions themselves.
Shortly thereafter, Tanaka and one Ikuo Tokunaga—an engineer who joined Seiko in 1970–put together a research team to tackle the problem. What resulted from this five-year exploration included the issuing of twenty new patents and the creation of the Professional Diver’s 600m (6159-022).
While brands like Rolex and Doxa solved the issue with the creation of a helium escape valve, Seiko took a very different approach. Among the many innovations, perhaps the most important was the creation of an L-shaped gasket which simply prevented the gas from entering the watch. However, to better withstand the rigours of the workplace, the watch was also constructed of titanium and housed in puck-like mantle that made it lightweight, corrosion proof, and highly resistant to both shock and magnetism.
The odd tin can shape would eventually give birth to its nickname, the Tuna. Three years later, it would also be fitted with a quartz movement and reign supreme as Seiko’s flagship professional diver until 1986.
Two years ago, it was re-released as the limited edition SLA041 and the more affordable SRPE29/31 and SRPF81/83 lines. It is also available in quartz as the SBBN031/33 and other references.
The 6105-8000/811X (1968/70)
Equally legendary, for different reasons, would be the next iteration of Seiko’s 150m diver, heretofore known as “The Captain Willard.” Originally developed in 1968 as the 6105-8000, it was the later 811X model that would prove more popular. Its unique, robust cushion case construction, competitive pricing, and ready availability in PX stores made the 6105 a hit among American servicemen fighting in the Vietnam War. It was so commonplace, that Martin Sheen’s character—Captain Willard—was outfitted with one in the 1979 film Apocalypse Now—retroactively providing the watch with its moniker. However, more than the sum of its eventual stardom in popular culture, the 6105 should be noted for the exceptional build quality and value proposition it presented. The Seiko diver, as an everyman’s watch, might well find its genesis here.
Future incarnations included the 6306 and 6309 references, which featured a slightly different form of the cushion case and became better known as the Turtles. The 6309 made its own movie debut—albeit somewhat less iconic—on the wrist of Ed Harris in The Abyss. While Seiko stopped making the watch in the latter half of the 1980s, they recently brought it back in 2016 in the form of the SRP77X and even reissued the Willard in 2020 (SPB151/153).
The 1980s and 90s
During the next two decades, Seiko’s popular 150m divers would get a bump up to 200m of water resistance. Quartz, kinetic, and solar would all make an appearance as the brand continued to progress. In 1986, the Prospex Diver’s 1000m (7C46-7009) would become the first watch to employ ceramic, which it used to replace its previous titanium shroud. The water resistance rating was now good to a full kilometer under the seas, and the watch employed a quartz movement. It garnered the nickname, the Golden Tuna, owing to its gilt highlights. The Scuba Master, released in 1990, announced the company’s foray into digital diving technology, and by 1995, Seiko had produced divers with depth gauges, thermometers, and kinetically powered quartz which no longer required a change of battery.
And then, of course, came a little thing called the SKX…
The SKX or 7S26
The SKX can trace its DNA back to the late seventies with the creation of the 150M Diver’s 7548 and on through the 7002 in 1988. But it wasn’t until 1996 that the iconic value proposition came into its own. In some respect, it picks up where the 6105 and 6309 left off—as an affordable beater and a capable diver. For even though Seiko had been pushing the limits of dive watch technology and driving innovation in the field, in some respect, their brand name was forged in the trenches (both literal and figurative) on more pedestrian fare. No other Seiko diver embodies this notion better than the SKX in all of its iterations.
A beater, simply put, is a watch you can comfortably wear, knock, ding, bump, and scratch without losing any sleep over it. One might argue—if you have ever encountered a tropicalized dial with a faded bezel and battered case—that a beater only improves by way of character with each new notch. A beater need only be three things: functional, durable, and…inexpensive. In short, the SKX.
By no means a perfect watch, the SKX was furnished with the 7S26—a 3Hz movement that was reasonably accurate but did not hack. It met and surpassed ISO 6425 standards but employed Hardlex rather than sapphire glass. Its lume was legendary, but its markers were painted and not applied. Its bracelet jangled. The watch spawned a mod culture like no other.
But the SKX succeeded in achieving something that is very difficult to quantify. It met with some unwritten litmus test that measures not only value for money, but cachet. The SKX was like a secret handshake among aficionados. And I would argue that this same arcane system of evaluation can be applied to a number of Seiko divers—before and after.
One of the things I find most endearing about Seiko dive heritage is the practice fans have adopted in naming the various watches. Seiko employ an opaque numbering system, but this has somehow opened the door for enthusiasts to participate in the process–and they do. You can watch it play out in different forums. It says something about the relationship between the brand and its collectors.
And so here we are…
The Monster, the Samurai, the Sumo—and the brand’s association with PADI—would all follow in the new millennium. The back catalogue would be cracked open and exploited to great success, more recently. Innovations would continue to be made. And the SKX would be retired.
But, perhaps, that is all part of the Seiko master plan. Anyone else out there thinking of a 30th anniversary edition of the SKX for 2026? Now, don’t go spreading rumours.
There are more than one hundred different Seiko divers in the Prospex Series today. They come in all shapes and sizes. They come in all manner of price points. They all come with history and capability. And more than a few come with that aforementioned cachet of cool. You need only choose your adventure.
Dev, John. The 62MAS 010. 1 September 2019. https://thespringbar.com/blogs/guides/seiko-62mas-010-first-divers-watch/. 18 April 2002.
Enloe, James. A Look at Seiko’s Early Diver’s. 04 February 2013. https://wornandwound.com/a-look-at-seikos-early-divers/. 18 April 2022.
History and Information of Seiko Diver’s Watches. 2022. https://chronodivers.com/history-of-seiko-divers-watches/. 18 April 2022.
Ryugo, Sadao. The Birth Of The Seiko Professional Diver’s Watch . Japan, 2021.
Stockton, Michael. Seiko 62MAS – The First Professional Diver Watch By Seiko. 06 March 2017. https://www.gearpatrol.com/watches/a180423/seiko-tuna-can-watches-you-should-know/.
The History of Seiko Diver’s Watches. 2022. https://www.seikowatches.com/global-en/products/prospex/special/historyofdiverswatches/. 18 April 2022.
The History of Seiko’s Iconic Diver’s Watch Collection. 22 March 2022. https://divemagazine.com/scuba-diving-equipment/seiko-dive-watch-history. 18 April 2022.
Special thanks also go to Pere ( @peteflay ) and Adam ( @aviation_watch ) for their personal contributions and support.
About the author
Brent Robillard is a writer, educator, craftsman, and watch enthusiast. He is the author of four novels. You can follow him on Instagram.
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16 thoughts on “Other Watchy Bits: A Brief History of Seiko Divers”
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Great article Brent! Hard to deny the appeal of an affordable tooly dive watch such as Seiko makes. Dare I say, they are the g.o.a.t. at this segment?!
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An argument could certainly be made. Thanks for the feedback!
Great article. I had a very rough idea about the Seiko diver lineage but definitely didn’t know as much as I thought. I’ll definitely be using this a reference
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Really glad you found it useful
Very interesting! I love my 5H26 quartz that I got in 1990.
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The 90s were the heyday of Seiko divers.
great article, very insightful
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Good reading mate! Already waiting for the SKX anniversary edition. Haha!
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Hmm…I thought I said, “No rumors…,” lol
I know the history but anytime there’s an article on seiko history I have it read it and it makes me appreciate all the vintage seikos I’ve owned and still have now. Especially my vintage seiko divers. Great write up bro.
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So glad you enjoyed it. Thanks for stopping by.
Wow! Very cool article. Thank you!
Cheers. Thanks for stopping by!
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