History of the Seiko Tuna Dive Watch

The history of Seiko Diving Watches goes back to 1965 with their very first model. From then on Seiko have lead the way in innovation, design technology, materials and style. You may have already looked at the Seiko Turtle and the Seiko Samurai dive watch – here we take a quick look at the groundbreaking Seiko Tuna dive watch.


Of all the Seiko ISO rated dive watches the Seiko Tuna has the most distinctive / original design, in fact, possibly of all the dive watches on the market (exception Omega PloProf). This unique design comes more from necessity than aesthetics. The key to this styling lies in the depth this watch can withstand. The Seiko Tuna range (that’s a nickname – not an official Seiko nomenclature) is a PROFESSIONAL diver’s watch capable of withstanding the pressure from depths of 600m (now 1000m). When diving at these depths a combination of mixed gases are used to protect the diver’s from “the bends” (1).

Seiko Tuna 1000m dive watch with distinctive helium gasket - click for sales
Instantly recognisable with external helium gasket – Seiko Tuna 1000m dive watch

New & Used Seiko Tuna for sale

There are dozens of new & pre-owned Seiko Tuna watches available on eBay. Click the button below for a filtered selection of the best Seiko Tuna available today

Helium Release Valve – superfluous

A proportion of these mixed gases is HELIUM. And there lies the problem. Helium particles are TINY … really TINY. They are small enough to enter the casing of a watch water resistant to even 600m. The problem arises during decompression. The helium gas cannot get out quickly enough. There is a build up pressure inside the watch which may cause the glass to blow off.

Titanium casing & special gasket

Seiko looked outside the box for solutions. Instead of looking to ways of allowing the helium to get out … they stopped it entering in the first place. With a specially designed gasket and the titanium monochoque casing the problem was solved in a unique fashion. That was back in 1975 that the world was first introduced to the Seiko Tuna. The initial watches were driven by Seiko’s 6159 Calibre (3) – 26 jewel – automatic movement.

Seiko Tuna – with a history back to 1978

The history of the Seiko Tuna goes back, way back to the late ’70s. In fact, it was in 1978 that the Seiko Professional Diver’s 600M became the world’s first saturation diving watch featuring a quartz movement in 1978.

The Seiko Tuna dive watch showing it's helium resisting external gasket
Photo courtesy of SeikoWatches.com

Driven by the 7549 calibre the Seiko Tuna was establishing itself as THE professional divers watch. In fact, to reinforce it’s superiority and prove it’s reliability Seiko undertook an amazing test. For instance, in 1983 the Seiko Tuna with 7549 quartz movement was was strapped to the research submarine “SHINKAI 2000” (5). Accordingly, down it went to an official depth of 1,062 meters below sea level. To emphasize, that’s nearly twice the maximum depth this watch is rated to. Needless to say, the Tuna performed with perfect accuracy. Due to this outstanding performance the Tuna booked it’s place in the Dive Watch Hall of Fame – and for very good reason.

200m to 1000m

The current line up of Seiko Tuna can withstand dive depths from 200m to 1000m. Since their introduction in in the late 1970’s the Tuna has been produced with all available Seiko movements from automatic (self winding), quartz (battery), kinetic (self charging) and solar.

A tribute to the Seiko Tuna by Steeldive

HOMAGE to the Tuna – Customers who admire the aesthetics of the Tuna dive watch may also like the Steeldive Tuna homage version. Not a fake, moreover a respectful and affordable tribute to this innovative dive watch. The watch below is available from the Steeldive UK official dealer (VJS Ltd)

STEELDIVE SD1978 Emperor Tuna 52mm Automatic 1000m Diver Watch *UK SELLER*

Nicknames of the most popular Tuna models

If you are looking for a watch with a witty nickname – that’ll be the Tuna. Here’s a few: the Darth Tuna (all black version), Mini Tuna (correct, it’s a bit smaller) , Emperor Tuna, Yellow Tuna (yellow bezel and accent on hands) all the way back to aptly named original Grandfather Tuna

What to pay for a pre-owned Tuna

A question visitors ask everyday – how much should I pay for a used Seiko Tuna. It’s all down to popularity, rarity, provenance and condition. Let’s start at the TOP end of the market. Don’t forget these watches are some of the finest timepieces in the world – in my view equalling the quality of some Swiss brands. The Seiko Sbdb013 Spring Drive Tuna Marinemaster is not going to give you any change from £2,500. If it says MARINEMASTER on the dial and it’s genuine, the starting price has to be around £1,000 for a “basic” automatic model. However, there are plenty of other versions available in particular, the solar and street Tuna models starting at £250.

Current Tuna models

Seiko refresh their Prospex dive watches quite frequently. While writing this article (June 2020) there were just 4 versions of Prospex dive watches with the “Tuna can” style case. Namely the S23627J1 and S23626J1 are two limited edition models with the 7C46 quartz movement. However, these two models are quite hard to find being collectors items. Currently, prices range from £2,000 to £2,700. For a more modest budget of around £600 there is the SRPA83K1 with a water resistancy of 200m – driven by the bomb proof Calibre 4R36 automatic movement.

My personal favourite is the Seiko SBDX014G. This Marinemaster professional dive watch is certified to 1000m. Furthermore, for £3,250 you get the luxurious mechanical calibre 8L35 automatic movement with 26 jewels providing an accuracy of +15 to -10 seconds per day and a 51 hour power reserve.

A Seiko S23627J1 Quartz divers watch in black and rose gold
Seiko S23627J1 – 1000m – 7C46 Quartz
A Seiko S23626J1 Prospex Tuna dive watch shown in black and bronze
Seiko S23626J1 – 1000m – 7C46 Quartz

A PADI version of the Seiko SRPA83K1 Tuna shown here in Blue with automatic movement
Seiko SRPA83K1 -200m – 4R36 Automatic
A stunning example of the top Seiko SBDX014G with automatic 8L35 high beat movement
Seiko SBDX014G – 1000m – 8L35 Automatic

Example Tuna Specification a Seiko SBDX014G

Case Material

  • Ceramic/titanium (hard coating) with stainless steel bezel

Glass Material

  • Sapphire

Band Material

  • Silicon

Case Size

  • Thickness: 17.2㎜
  • Diameter: 52.4㎜
  • Length: 53.5㎜

Calibre Number

  • Calibre 8L35

Movement Type

  • Automatic with manual winding capacity


  • Approx. 50 hours


  • +15 to -10 seconds per day


  • Lumibrite on hands and indexs

Water Resistance

  • 1000m / 3300ft for saturation diving

Other Features

  • 26 jewels
  • Date display
  • Screw-down crown
  • Stop seconds hand function
  • Unidirectional rotating bezel

Seiko Tuna Videos

Seiko Prospex Marine Master Professional SBDX014G

Peter Manthos take on the awesome Seiko Prospex Marine Master Professional SBDX014G


Seiko PADI Monster Tuna – SRPA83K1

Watch Videos – a full review of the PADI baby Tuna 200m dive watch


Authorised Seiko Prospex shopping partner

Our online shopping partner sells the entire range of Seiko Prospex dive watches. Shop with confidence at Jurawatches. Get the assurance of a genuine Seiko Prospex watch from an authorised dealer.

This is what our shopping partners say about the Seiko Prospex range

“Discover our stunning collection of Seiko Prospex watches designed especially for sport lovers and adventurers in mind. Since the first Seiko Prospex Divers watch was released in 1965, the brand have continued to challenge and expand on their designs to create a range of Japanese diving and sport watches that provide exceptional functionality and striking visual appeal”


If you found this page via a search engine – please visit our generic Seiko Divers watch history page for more information on all Seiko Prospex models since 1965. There’s general information on all iconic styles from Japan’s leading manufacturer of quality dive watches. If you are in the market for a new watch then please browse the hundreds of Seiko Diving Watches for sale here.

External references / further reading