If Seiko’s early “Tuna” references seem over the top, well, that’s because they are. More than just a dive watch, the first “Tuna” model was a response to harsh, albeit deserved, criticism. After the success of the 150m 62MAS in 1965, Seiko doubled down and set out to engineer their first true professional diver. The resulting 6215, and hi-beat 6159 models were built to withstand conditions at 300m. Both were large, imposing designs with solid monocoque cases that performed well in controlled environments. However, in 1968, a saturation diver from Hiroshima penned a letter to Seiko informing engineers of the many shortcomings in construction experienced during real world applications. Rather than admit defeat and bow out, engineers at Seiko saw an opportunity to rise to the occasion and not only meet these challenges head on, but to exceed all expectations. They spent the next seven years developing the perfect professional diver’s watch. In that time, more than 20 patents were applied for and granted in the process. The result was unveiled in 1975, and what we now refer to as the “Grandfather Tuna” was a checklist of diver’s watch innovation. With a rating of 600m, it’s features are too many to list here, and it surpassed every ISO testing standard available. Just three years later with the advent of quartz technology, Seiko went back to the well and delivered it’s first quartz driven “Tuna” diver. It shares many characteristics with its predecessor, however, to further improve durability, it’s titanium case was plated in a super ceramic titanium nitride plating that spurned yet another nickname: the “Golden Tuna.” So named for their resemblance to actual cans of tun, these shrouded divers are still very much a part of seiko diver identity. Early variants are list toppers for collectors, and the build quality alone means that many not only survived, but have remained in great cosmetic condition even decades later. This example from March of 1981 is exceptional. In near mint condition, it appears that it has spent the last 40 years tucked away for safe keeping. It’s completely original aside from a replacement coil, and after servicing and a fresh battery is operating perfectly. The original GL-831 strap has no tears or breaks, and the original hardlex crystal is flawless. For collectors, this is a dream example. It doesn’t get any better. 

Original Seiko GL-831 Straight Vent Black Rubber Strap with Original Buckle

Serviced 3/28/20

Diameter- 49mm

Lugs- 22mm