It’s likely that no other reference better serves as the embodiment of “Seiko Diver” than the 300m Tuna. If for no other reason, its longevity makes it the clear front runner. For more than four decades, some evolution of the original 300m Pro Diver “Tuna Can” has continued to serve the Seiko faithful since it’s inception in 1978. Today’s “Marine Master” may have modern detailing and technological tweaks, but the lineage and identity is undeniable. It’s this instant recognition, regardless of age or era that makes a good tool watch great. Materials and technology evolve, but the overall design remains static. And when well executed, that design becomes timeless. Setting that tone for Seiko, was the 7549-7010. It wasn’t the first of the Tuna Can models, nor was it capable of reaching the same depths as its bigger brethren. It was however, easily the most versatile. The “Grandfather Tuna” was nothing if not capable, but it’s 600m depth rating meant strapping a veritable hockey puck to your wrist at more the 50mm in diameter. The “Golden Tuna” offered some reprieve, housing a quartz movement, but that made little more than a single millimeter difference in case size. Though both were well received, they were purpose built without compromise, and that meant neither had any chance of sliding under a shirt cuff. The success of both enticed Seiko to develop the 300m variant. Choosing a more typical screw down case back design over a monocoque style, lowered the depth rating, but also the overall height by a full millimeter (miles by watch standards). The new design also shaved 2mm off of the diameter, and quite a few dollars off the price point for consumers. Seiko had hit a sweet spot for the Tuna Can, and made an impression that has successfully lasted more than 40 years. Getting your hands on a modern 300 is certainly a worth while venture, but for many, owning the original is a goal worth setting. Good examples aren’t impossible to find, and this one from February of ‘81 checks all the boxes. The matte black dial is absolutely perfect with just a touch of creamy patina in the large luminous plots. The hands have retained their brightly polished finish, and original luminous with only a touch of color in the corners of the minute hand . The bezel action is smooth, and the insert shows very little wear. The original shroud is secured by the original screws, and the factory sandblasted finish is still visible. There is a moderate scrape between the 8 and 10 o’clock screws on the shroud, but it is otherwise free of noticeable wear. The crown and case back screw down securely with ample threading, and the crystal is the original domed hardlex that has been carefully hand polished to remove most scratches. It’s unpolished and completely original, and post service with a new battery, it’s keeping perfect time. We’ve paired it with an Uncle Seiko Oxidized GL-831 for a fit and finish that’s as true to the original as possible. A Seiko diving legend, it’s sure to be your favorite tool in the box.

Uncle Seiko Oxidized GL-831 Black Composite Rubber

Serviced 10/13/22

Diameter- 47mm

Lugs- 22mm