The Seiko Tuna has become synonymous with Seiko’s top-of-the-line diving innovation. With its immense water resistance and no-nonsense specifications, it has always been one of the most capable dive watches on the market. Seiko has updated the quartz Tuna with a pair of new and perhaps perfect models for a professional diver.
The term ‘Tool Watch’ is far too often used. The fact is that neither a Rolex Submariner nor an Omega Seamaster is a true tool watch. These are luxury watches capable of undertaking the role of a tool watch. However, the Seiko Tuna is a watch which truly couldn’t be much more of a tool — a point which the two latest references of Tuna certainly maintain.
Within the Seiko Tuna collection are, more or less, three families: The 200m, 300m and 1000m collections. The 200m water resistance models are often regarded as not really being true Tunas as they are not saturation divers whilst the other two collections are just different levels of intensity of the same concept. This concept is to be a robust dive watch with a bezel and case protected by a screw-on shroud and with the ability to be used for saturation diving. After all, that last point was the very reason for the Seiko Tuna’s development from 1968 to 1975.
Released in the 1980s as a more manageable alternative to the full-fat Tuna dive watch, the 300m variant has always been powered by an accurate and durable in-house quartz movement which features and end-of-life indicator to ensure diving security. In many ways, this makes real sense for a serious dive watch. The new modern iteration offers a rather stunning play on the concept in brushed and polished stainless steel in the form of the S23629.
Looking at this piece, you really get all the dive watch you could want with a full-graduated bezel protected by a steel shroud and a covered luminous pip in order to prevent damage. Whilst the water resistance is ‘only’ 300 metres, this watch is also rated to resist helium ingress and so can be used for saturation diving, should you need it to be. Most importantly, the 300m Seiko Tuna also features a screwed caseback thus making the battery change easier when it comes every 5 years.
Alternatively, if you view 300 metres as barely the depth of a paddling pool then it’s the S23631 which is the watch for you. Tracing its lineage back to the 1000m water resistance quartz Seiko Tuna 7C46-7009 of 1986, this watch has an altogether more serious specs sheet. For a start, as is the case for all of the top-end Tunas, the case is titanium with a ceramic shroud to absorb knocks and scratches. This is also a monobloc case which means that the movement is services and loaded through the front, thus removing the need for an opening caseback.
Inside both of these watches is one of the best technical quartz movements on the market: the Seiko 7C46. This 7-jewel movement with the day, the date, high torque and an end-of-life indicator is not to be confused with affordable quartz movements. This is a movement chosen for reliability, accuracy and durability rather than cost cutting. Importantly, the high torque of this movement was in important feature when selecting the hands of these watches.
Aside from having a redesigned set of applied metal markers filled with Seiko’s famously-bright ‘Lumibrite’ compound, Seiko wanted the hands to be particularly legible. For this reason, the large minute hand of the original Tunas (albeit in a modern form) was reintroduced with the similarly gargantuan portion of luminous coating. The result will, no doubt, be a pair of the most functional, legible and practical dive watches of the year. Of course, these are more expensive than some other Seiko dive watches but the reality is that these aren’t just some of the best dive watches made by Seiko but some of the best dive watches altogether.
Availability: Available from July 2020: S23629: USD 1,450 / S23631: USD 2,400
- Dimensions: S23629: 47.7mm / S23631: 49.4mm
- Material: S23631: Titanium & Ceramic / S23629: Stainless Steel
- Display: Hours, Minutes & Second / Day & Date / Applied indices / Lumibrite on hands & dial / Unidirectional luminous dive bezel
- Water Resistance: S23629: 300m, 1000ft, 30 ATM / S23629: 1000m, 3300ft, 100 ATM
- Movement: Seiko cal. 7C46: Quartz / Time, Day & Date / End Of Life Indicator / 5-year battery life / 7 jewels / Hacking