There are few iconic moments that can match the sheer reach of James Earl Jones’ epic line “No. . . I am your Father” and the character he’s voicing from the immense Star Wars saga Darth Vader is surely one of the most recognisable baddies the world has ever seen. The Seiko SBBN025 Darth Tuna can’t claim such world recognition, but in our little horological universe those who know their stuff know the Tuna, or at least they should.

Tuna Can watches have a history that isn’t ancient but is significant. The shroud that led to the name was added to protect the case of the watch underneath. Simple yet effective. I don’t think any thought was given to aesthetic and this Seiko SBBN025 is named Darth because the ceramic shroud is black, and has a passing resemblance to Darth Vaders Helmet. It’s just a cool nick name that stuck. Confusingly the SBBN013 is also a Darth Tuna, as was the SBBN011 before it, and they are almost identical other than the dial, hand set and some other almost undetectable nuances. There are others too that are ‘Darth’, but suffice to say, if its all black, 1000m rated and has a 7c46 movement it’s a Darth Tuna.

1000m rated Tunas have a Monobloc case which is another historically significant feature. Designed between 1968-75 for saturation diving, Seiko developed a divers titanium case, ceramic shroud, L shape gasket and 17 other patents by request to achieve a watch that was “helium proof” for professionals engaged in this kind of activity. Beware though, to get into these monobloc cased “real tuna” watches you have to go from the crystal side, so prepare for a struggle to find anyone other than Seiko to get into it for a battery change. One of the early “Golden Tuna” models with the old 7549 quartz movement can be seen on Roger Moore’s wrist just before being thrown over board for a shark swim in “For your Eyes Only”.

The Tuna was first introduced in 1975, so of course by now there are loads of versions and finding the watch that’s right for you is a bit of a minefield that needs careful crossing. The price range is also confusing ranging from a few hundred to more than a few thousand pounds for the highest end spring drive and limited editions.

The 7c46 movement is described as ‘high tech’ and has a very high torque, metal parts and is designed to withstand the rigours of saturation diving. The movement is quoted at +/- 15 seconds a month but my watch has achieved +1.6 seconds in 147 days which is well within 9F territory. My 3 7c46 hit the markers all the way around.

The Seiko SBBN025 sports most of the wonderfully marmite function over form design features as the original, with the black Ti case, ceramic shroud, matt black dial and huge hands lumed to wake any light sleeper although hands on this one are a more modern shaped iteration.

The Unidirectional 120 click bezel moves firmly and has minute markers all the way around with lume at 12. With a 15.3mm height it’s far more wearable than its 8L35 automatic brother the “Emperor” at 17mm and even its 1975 “Grandfather” at 15.9. The 49.3 reported diameter (the case is circular) wears amazingly well as the strap has an invisible fitting under the watch. Alas there are no drilled lugs so if you do want to swap out the 22mm J22 strap supplied it can be a bit fiddly but the J22 is a very comfy strap, suits the watch perfectly. It weighs in at 118g.

The Tuna is utter marmite. Having owned my first over ten years ago, flipping it almost immediately, I didn’t realise the seeds were sown. It took almost another ten years to own another but these quirky, tonka toy, function over form, refusal conform to any trend or “rolex submariner” rule set by the cool club watches are just brilliant. I’m a huge fan.