Of all the Seiko ISO rated dive watches the Seiko Tuna has the most distinctive / original design. 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)


Counterfeit warning – shoppers must make their own judgement to determine the authenticity of any watch before buying it – avoid buying a fake watch

LIVE feed sales

UK sellers – updated 17th September 2019

Seiko Tuna - LIVE feed - UK sellers

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Available online now

Chronodivers.com is an affiliated partner of Amazon.com. Here’s a selection from their range of Seiko 200m dive watches (not specifically the “Tuna” case style)

LIVE feed sales

USA Sellers – updated September 17, 2019

Seiko Tuna - LIVE feed - USA sellers

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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.

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First Quartz 600m Dive watch – 1978

In 1978 The Seiko Professional Diver’s 600M became the world’s first saturation diving watch featuring a quartz movement in 1978.

Photo courtesy of SeikoWatches.com

Driven by the 7549 caliber the Seiko Tuna was establishing itself as THE professional divers watch. To reinforce it’s superiority and prove it’s reliability Seiko undertook an amazing test. In 1983 the Seiko Tuna with 7549 quartz movement was was strapped to the research submarine “SHINKAI 2000” (5). Down it went to an official depth of 1,062 meters below sea level. That’s nearly twice the maximum depth this watch is rated to. Needless to say – the Tuna performed with perfect accuracy.

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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, kinetic and solar.

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Current models

Seiko refresh their Prospex dive watches quite frequently. While writing this article (June 2019) there were just 4 versions of Prospex dive watches with the “Tuna can” style case. The S23627J1 and S23626J1 are both limited edition models with the 7C46 quartz movement. These two models are quite hard to find being collectors items. 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 4R36 automatic movement.

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

Seiko S23627J1 – 1000m – 7C46 Quartz
Seiko S23626J1 – 1000m – 7C46 Quartz

Seiko SRPA83K1 -200m – 4R36 Automatic
Seiko SBDX014G – 1000m – 8L35 Automatic

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Specification SBDX014G

Case Material

Ceramic/titanium (hard coating) with stainless steel bezel

Glass Material


Band Material


Case Size

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

Calibre Number


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

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Seiko Tuna Videos

Seiko Prospex Marine Master Professional SBDX014G

YouTube video

Peter Alexander Manthos – his take on the Seiko Prospex Marine Master Professional SBDX014G

Seiko PADI Monster Tuna – SRPA83K1

YouTube video

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

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External references / further reading

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If you found this page via a search engine – please pop over to our generic Seiko Divers watch page. You will find plenty more information on iconic styles from Japan’s leading manufacturer of quality dive watches.