In partnership with Seiko Prospex

Deep Dive: The Evolution of Seiko’s Shrouded Divers

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 brings us to the final chapter in our series: Seiko’s shrouded divers. These unique dive watches have been a cult favorite for decades, while also serving as a lab of sorts for some of Seiko’s most ingenious technology. Their unique shape is among the most distinctive in the sports watch landscape, and has morphed from ugly duckling to something of a style icon in a few short decades.

In the 1970s, as dive watches were becoming more common among the general public and manufacturing capabilities continued to advance, watch design took many unique turns. Highly specialized watches with novel features began to hit the market, and they didn’t look much at all like the divers that popularized the genre just a decade before. Among the most intriguing dive watches introduced during this time was the Seiko 6159-7010, the so-called “Grandfather Tuna.” This milestone timepiece was developed in response to a now-famous letter from a professional diver expressing a need for a true diver’s watch that could withstand the conditions and shock that it would be exposed to under deep water conditions and activity. Introduced in 1975, the “Tuna” was unlike anything else Seiko had ever produced, distinctively styled, but also paving the way for a long series of tech-forward designs featuring some of Seiko’s most interesting movements.  

Seiko 6159-7010, the “Grandfather Tuna.”
Note the iconic shroud.

The dominant design feature of the Grandfather Tuna and the watches that followed it is, without a doubt, the shrouded case design. On the 6159-7010, a titanium shroud, coated in ceramic, circles the bezel, providing an extra degree of protection from having the essential timing bezel jostled during a dive. Because the bezel is only accessible by hand, over a relatively small percentage of its total surface area, any adjustment of the bezel has to be extremely deliberate. In a way, this can be seen as a method of “locking” the bezel without an actual mechanical or physical locking mechanism being employed.

The Grandfather Tuna is distinguished by more than just a novel case design. It represents a significant leap forward in functionality, with a depth rating of 600 meters thanks to its monocoque, or one-piece, case design, and an L-shaped gasket which eliminates the need for a helium escape valve in a saturation diver. It also features a high-beat movement, and marked the debut of Seiko’s vented rubber dive strap, which has itself become something of an icon. All told, the Grandfather Tuna took seven years to develop and resulted in 20 patents on the exterior alone.

The “Tuna” was unlike anything else Seiko had ever produced, distinctively styled, but also paving the way for a long series of tech-forward designs featuring some of Seiko’s most interesting movements. 

The Seiko 6159-7010 has a monocoque, or one-piece, case design.

Following the release of the 6159-7010, shrouded divers became something of a cult favorite among Seiko aficionados, with plenty of notable references incorporating the shroud through the years. In 1978, just a few years after the first Tuna was launched, Seiko released reference 7549-7000, which would come to be known as the “Golden Tuna.” Featuring the same shroud design as the original Tuna, it added yellow gold accents on the bezel, crown, and screws. In addition, this version features a depth rating of 600 meters and is the first purpose-built saturation diver powered by a quartz movement. While quartz Tunas would become increasingly important to Seiko as the years went on, this first version is still most remembered, perhaps, as a Bond watch: it was worn by Roger Moore in 1981’s ​For Your Eyes Only​.

Seiko 7549-7000 “Golden Tuna.”

A conversation about historic Tunas is not complete without a discussion of the SBDX011, the “Emperor Tuna,” released in 2009 exclusively to the Japanese market. Bearing a Marinemaster signature on the dial, this is, clearly, a very serious instrument. Blacked out and sleek despite its 50mm case size, the SBDX011 used an automatic movement and was certified to a depth of a staggering 1,000 meters. This watch, as much as anything Seiko has produced, represents the brand creating something just for the sake of pushing its own engineering capabilities to the limit. A thousand meters is a long way down — much further than any human would need a watch to function. But Seiko built it anyway. In fact, when tested,​ ​it was found that the watch could withstand even deeper depths​. Much deeper. Take a look.

One of the most popular Tunas among collectors are the “Tuna Cans,” which feature a slimmer, more compact design. Reference 7549-7010 introduced the new form factor back in 1978, and years later reintroduced the design in the form of the SBBN015. It isn’t quite as spectacularly engineered as the Emperor Tuna, but it more than holds its own with its thermo-compensated, high-torque 7C46 quartz caliber.

Seiko 7549-7010 “Tuna Can.”

Not all shrouded divers are defined as “Tunas” by collectors. One of the most iconic watches to feature this design note is the H558, introduced in 1982. Commonly known as the “Arnie,” this watch was worn by none other than Arnold Schwarzenegger in several films, including ​Commando ​and ​Predator. As you’d expect, this watch is tough. The H558 is also one of the earliest “ana-digi” watches to gain serious market traction. Developed by Seiko to withstand temperatures between -40C and up to 60C, this extraordinarily durable watch made it to the peak of Everest as part of a 1988 expedition and has seen time at both the North and South Poles.

A vintage “Arnie” with a rare orange dial, Seiko H558-500a.

The H558’s prevalence in our popular culture  makes it one of the most enduring watches in Seiko’s back catalog, so it’s no surprise at all that it was recently reimagined under the Prospex banner, featuring a state-of-the-art solar-powered movement. The new  “Arnie” models not only give fans of ’80s action flicks a chance to own a small piece of history, but still hold up as an incredibly useful multifunction timepiece, complete with alarms, a calendar, and superior legibility. This includes the SNJ025, a direct homage to the original H558, a PADI Special edition (SNJ027), and an e-commerce exclusive version (SNJ028). The “Arnie” models are great examples of how heritage pieces can be reborn within the Prospex line.

Seiko SNJ025 “Arnie.”

Prospex is also the home to Seiko’s current collection of Tuna-inspired shrouded divers. The Tuna nickname, of course, still stands, now describing an exciting series of watches aimed at both long-time Seiko aficionados and those who might be interested in starting their own collections.

Seiko SNE498.
Seiko SNE499 PADI edition.

A thousand meters is a long way down — much further than any human would need a watch to function. But Seiko built it anyway.

The SNE498 and SNE499, for example, can be thought of as the contemporary iterations of the much loved Tuna Can, SBBN015. The 498 offers a black shroud, black dial and golden accents (a nod to the “Golden Tuna”), while the 499 is the PADI special edition (celebrating Seiko’s link to professional diving), with highlights in red and blue. Now featuring solar-powered quartz movements, these new Tunas are a convenient option for anyone seeking a tough weekend watch – or maybe something to bring along on vacation where there’s a high probability of getting wet.

If you’re looking for something more youthful and fashion-forward, these watches are also available as part of the Seiko Street Series, presented in an array of attractive colors to allow wearers to express their own unique styles. The Street Series versions also feature lightly textured dials for added  visual interest. They’re still serious diver’s watches, with all the functionality that goes along with that, but this new generation of shrouded divers are happy to be worn casually as well.

Seiko Street Series SNE533.
Seiko Street Series SNE543.

Seiko’s shrouded divers offer a rich history of innovation, and are emblematic of the spark of creativity central to the brand. No other series of watches in Seiko’s impressive lineup mixes tactical functionality with whimsy and fun in the way that these have throughout the years. While they are surely watches that hold a niche appeal, there’s still a watch for almost anyone within the shrouded diver design.

To learn more about Seiko’s Prospex range, visit

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