For their toughness, utility and raffish good looks, diver’s watches are arguably the ultimate timepieces for everyday wear – the hulking marked bezel that protects the crystal in unfortunate meet-ups with door jambs and the other person’s watch also tracks elapsed timings for everything from journeys to the doneness of one’s eggs; and the watch is built to shrug off punishment from a wide range of sports activities with nary a concern. A dive watch is ever true to its function, under most conditions and occasions. And among the multitude of dive watches, a handful stand out as icons of this beloved genre, including the Seiko “Tuna”.

The Seiko Tuna makes a huge style statement even from across the room because it looks like no other. Reminiscent of the concentric walls of ancient fortifications, the Tuna’s defining trait is an outer case screwed to the actual watch case, resulting in a profile that resembles a can of tuna – hence the nickname.

Seiko did not create the Tuna for the sake of making it look different. Rather, it was to solve a problem encountered in saturation diving. Dive watches test fine for the depths they are rated to, but in saturation diving where professional divers spend prolonged periods living in highly pressurized air chambers between dives, helium slips into perfectly waterproof watches. During the decompression phase at the end of the dive, as the ambient air pressure is lowered to normal atmospheric pressure, the helium under pressure in the watch wants to escape, just like air held in a balloon. As a result, the watch crystal can pop off explosively.

There are two ways to solve the problem: put a helium escape valve in the watch so that the helium can escape during decompression, a solution that was developed by Rolex and Doxa in the 1960s; or build a watch so tightly sealed that it is not only impervious to water, but also sealed against the ingress of smaller helium molecules. This was the route that Seiko took, and the result is the creation of the first Seiko Tuna in 1975.

Seiko Tuna

Over the years, the Tuna has been continuously updated in terms of technology and aesthetics, greatly broadening its appeal beyond the community of saturation divers. Tunas have been fitted with a wide range of Seiko movements, spanning automatic, quartz, Kinetic, Spring Drive; they have also been made in a range of case sizes compared to the original’s 51mm; and sported a range of colours. A Tuna is not just one watch but a diverse collection to address the varied performance requirements and style preferences of the collecting community, while staying in step with the design cues of the 1975 original.

Prospex Diver’s Watch Limited Edition SRPD14K1 “Yellowfin Tuna”
Prospex Diver’s Watch Limited Edition SRPD14K1 “Yellowfin Tuna”

For collectors in the region, Seiko has released a new Tuna, the Prospex Diver’s Watch Limited Edition SRPD14K1 “Yellowfin Tuna”, in a limited edition of 2,200 pieces, exclusively for Singapore, Hong Kong, Malaysia, Brunei and Macau. The brown dial complements the rose gold tint of the stainless steel outer case, matched with a “snake belly” silicone strap. Beating within is the self-winding cal. 4R36, derived from the 7S26 which drives many of Seiko’s watches, with the added facility of hacking seconds for more accurate time setting, and hand winding.

At 42.9mm, the Yellowfin Tuna is of a more wearable size for many, and the 200m water resistance is ample for much outside of saturation diving. The Yellowfin Tuna SRPD14K1 is available at Seiko boutiques, City Chain and authorized dealers in Singapore, at a suggested retail price of S$775.80.

Technical Specifications


Self-winding cal. 4R36 with hacking seconds, handwinding and 40 hours’ power reserve


42.9mm stainless steel with rose gold tint; water resistant to 200m


Snake belly-style silicone band

Prospex Diver’s Watch Limited Edition SRPD14K1 “Yellowfin Tuna”