In partnership with Seiko Prospex

Deep Dive: The Evolution of the Seiko Turtle

Seiko has a long history of making superior dive watches perfect for pros, weekend enthusiasts, and everyone in between. In this three part series, we’ll take a look at the histories of three distinct dive watch families under the Seiko umbrella – timepieces so iconic and treasured by watch aficionados that many have their own, unofficial nicknames – and track their evolution to today’s most modern, tech forward, Prospex iterations.

Today, our focus is on the “Turtle,” and the long history of Seiko’s vaunted, highly functional tool watch for the common man.

For years, the watch community has acknowledged that the Seiko dive watch is an essential tool for any serious collector or enthusiast. Over the past decades, Seiko has produced a series of dive watches with equal appeal to the most dedicated collectors and the larger watch buying public. Unlike some of Seiko’s Swiss rivals, the Japanese brand has long been known for creating watches with case shapes and features that make them distinctive — these are not, necessarily, what you picture when you close your eyes and imagine a watch, and they’re that much more prized for that.  

The “Turtle” — Seiko’s long-revered, cushion-case dive watch — is a great example of a timepiece that’s just strange enough to stand out, but so outstanding that its quirks are not only accepted, but lovingly embraced. From the earliest 6306 and 6309 references, to the modern re-launched SRP series in the Prospex line, the Turtle has been an entry point to Seiko divers, representing the everyman’s choice, while still able to measure up to its professional counterparts.

A Scubapro-branded Seiko 6306.

The story of the “Turtle” begins in 1976 with the reference 6306-7000/1, released for the Japanese market only. With a depth rating of 150 meters, this watch could easily meet the needs of a recreational diver, or just about anyone else who desired a daily wear timepiece they wouldn’t have to worry all that much about. Comparisons with the current generation SRP Turtles reveal that little has changed — Seiko’s original design worked in the mid-70s, and it works now.

Powered by Seiko’s 6306A caliber, the 6306-7000/1 sported a 60-click bezel encircling a black dial with oversized lume plots in a mix of circular and more ornate shapes. Because the watch was made for the Japanese market, it features an English/Kanji day-date wheel, a feature treasured by its fans.

From the earliest 6306 and 6309 references, to the modern re-launched SRP series in the Prospex line, “the Turtle” has been an entry point to Seiko divers, representing the everyman’s choice, while still able to measure up to its professional counterparts.

The 6309-7040/9 is essentially the worldwide version of the 6306-7000/1, and while the JDM  watch is much rarer than the 6309, the differences between the two are minimal. Perhaps the most notable change is the 6309A caliber movement, which has a lower jewel count than the 6306A and does not include a hacking seconds feature. Otherwise, the two models are essentially identical, with the movements proving reliable and robust over the decades. In fact, these are among the movements that have created the widespread idea that Seiko calibers are almost indestructible.

The legendary Seiko 6309 dive watch.

The design of both the 6306 and the 6309 is distinguished by an unusual case shape. While it has the appearance of a traditional cushion case, the corners are rounded off in a way that gives the watch a less aggressive and more inviting shape. Despite the watch’s heft, it looks comfortable enough to wear all day. The sloping lines make the watch easy to wear under a shirt sleeve, and also give it an organic feel. The “Turtle” nickname stems from this oblong, softly curving appearance, resembling a turtle shell when viewed from above. Of course, the fact that the turtle is an amphibious creature, and the 6306 and 6309 are built for the water, doesn’t hurt either.

Partly because of their extraordinary durability, these early Turtles have attained a certain level of cultural significance – becoming a go-to watch throughout much of the 1980s. As a pop-culture symbol, the Turtle most famously appears in James Cameron’s ​1989 film, The Abyss, with a 6309 appearing on actor Ed Harris’ wrist throughout a film fittingly set underwater. But the Turtle is versatile in the cultural realm as well – in fact, Mick Jagger has also been known to wear one.

The early ’80s saw the appearance (and quick disappearance) of the reference 6309-7290. This transitional model featured small changes to the familiar Turtle shape and served as the beginning for an entirely new series of watches that would become iconic in their own right. Known to collectors as the “Slim Turtle,” the 6309-7290 has a sharper and more angular case, and overall trimmer profile. It’s sleek and angular where the 6306 and 6309 are more softly rounded. The Slim Turtle first appeared in 1982, having a production run of just a few years. In the nearly 40 years since the watch was introduced, it has become extremely collectible, and notably difficult to find. Part of its appeal, in addition to its place in the Turtle line, is that it also​ represents the first glimmer of what would later become the SKX007, perhaps the most popular accessibly priced dive watch of all time.

The iconic Seiko SKX007, one of the most beloved dive watches ever created.

After a period of dormancy through the 90s, while Seiko shifted its focus to the SKX007 and its many variants, as well as the development of a variety of non-mechanical timekeeping technologies, the brand relaunched the Turtle in 2016 to great acclaim. Now part of the Prospex series of technically-advanced, high-grade functional watches, the updated version of the original 6309 was an immediate hit. In fact, longtime Seiko lovers were immediately over the moon with how closely tied the new designs were to the original watches. With a case size of 45mm, the new Turtles are only about half a millimeter larger than their vintage inspirations, and feature handsets and dial elements nearly identical to those of the 6309.

Old versus New: A Seiko 6309 next to a modern Seiko Prospex SRP777.

Now part of the Prospex series of technically-advanced, high-grade functional watches, the updated version of the original 6309 was an immediate hit.

The primary differences are technical. The new SRP series replaces the well-known “Water Resist” 150 meters designation on the dial with the Prospex logo which signals the upgraded water resistance rating of 200 meters. The movement is still a rock-solid in-house caliber developed by Seiko, but includes modern components to keep the watch at peak performance for greater periods of time. The modern SRP is the best kind of vintage reissue: it gets the aesthetics exactly right, and the tech is good enough that you don’t have to give it a second thought.

Seiko Prospex SRP777.
Seiko Prospex SRP777.
Seiko Prospex SRPA21 PADI Edition.
Seiko Prospex SRPD21 Save the Ocean Edition.
Seiko Prospex SRPD21 Save the Ocean Edition.

With the Prospex SRP series, watch lovers – and Turtle fans – are able to strap on a piece of history that still feels modern. That’s a rarity in the watch world. Most new watches fall clearly into the camp of “vintage-inspired” or boast a bold new design that might have some swooning and others taking a hard pass. Because the 6306 and 6309 were so distinctive to begin with, the SRP watches still feel exciting and new, but have an undeniable tether to the watches that preceded them. Most importantly, at their core, these are still watches for everyone. Whether you’re the world’s biggest rock star or a weekend diver, the Turtle will feel at home on your wrist.

To learn more about Seiko’s Prospex range, visit

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