When it comes to diver’s watches, it’s hard to find another watch brand which has such a rich history and which contributed so much to the industry as Seiko. Perhaps Rolex and Blancpain come close. Seiko 62MAS and 6159-7001 in 1960’s, Seiko 6105 in 1970’s, various Tuna models in 1970’s and 80’s. All these watches are now iconic and all of them contributed a lot to the watch industry. They set standards and shaped the look of modern dive watches. To learn more about these watches, I recommend you checking out this article on wornandwound.com. My claim is especially true for the Seiko Tuna line. Originally, they were built as a no nonsense tool watch for diving. There were no compromises made, just one purpose to create a perfect dive watch: robust case, outer shroud for an additional protection, shatter proof crystal, highly legible dial, rotating diving bezel, great water resistance which was able to withstand much higher pressures than denoted on the specification.
However, over the years the purpose of diver’s watches diminished as they become replaced by diving computers. Diver’s watches had to evolve in order to stay in the picture. And so did Seiko Tuna lineup. Some changes had to be made to make them more wearable on everyday scenario. The cases shrunk and the profile got slightly lower; however, they still retained their high quality, impressive water resistance or their unique shroud. In my opinion, the pinnacle of a modern Seiko Tuna, which at the same time is still true to it’s heritage, is Seiko SBBN015. It was the last model with that rich Seiko pedigree, which all of us know and love. Unfortunately, later models had to many compromises such as plastic shrouds, lower overall quality, or lower, entry level movements. A good example is a limited edition Seiko SDN028 with Solar movement. Although this plastic shrouded diver still looks great, there were too many adjustments made to keep the price in check. I love Seiko as a watch brand but I feel it was as if Seiko wanted to score easy money by making Tuna dream cheaper and more accessible to masses. Of course, it’s nothing wrong in that because every company aims to maximize their income; however, it could put off some die-hard fans. That’s one of the reasons I think Seiko Tuna SBBN015 is the best diver’s watch Seiko has ever made, or at least the best Tuna variant they ever made.
Seiko SBBN015 comes in faux silver leather box with an outer cardboard box. Inside you can find all the paperwork, manuals, warranty card etc. Unfortunately, there is no extra accessories inside the box. I think Seiko could have added at least a spare rubber strap to make the package feel more premium. Nevertheless, the packaging is definitely a step up vs entry level Seiko watches. However, it’s still a long way to Swiss made watches. in the regard.
Seiko SBBN015 Tuna features a 48 mm case, and that includes the stainless steel shroud. It might look gigantic on paper but the watch doesn’t wear as big. There are two reasons for that. First is that is the fact that the case is almost entirely round, which mean that the lug to lug measurement is also 48 mm. Any lug to lug length below 50 mm for a diver’s watch is ok in my books. The second reason why SBBN015 doesn’t wear as big is the cone shape of the case and the shroud. 48 mm is measured at the base of the case/shroud and the watch is built in such a way that it tapers towards to top of the case. It makes it optically a lot smaller than you would think judging from the pictures. Therefore, SBBN015 will look great on variety of wrist sizes, I would say anything above 6,5″ will do fine with a Tuna.
What I really like about this Tuna case is its short lugs. They seamlessly integrate with the case, making them almost invisible. However, unlike 1000 m quartz Tunas (like SBBN013), SBBN015 has drilled lug holes. I think I don’t have to stress out how useful it is for strap changing. And trust me, you will change straps on these quite often as it looks great on anything you throw at it. But more on that later.
At 4 o’clock there is a screw down crown, which is nicely integrated with the shroud. It has a nice knurled texture to it and it operates buttery smooth. The crown is also signed with a beautiful S. It’s a small thing but adds some class to the watch. The newer generation of quartz Tunas, like SBBN031, has a simple laser etched crown, which takes some charm away.
Make a note that SBBN015 is a quartz watch, which means you will very rarely use the crown. That’s a good thing because there is less chances for you to forget about locking the crown in place before taking it into water.
The polished caseback of Seiko SBBN015 is screw-down and has some practical information engraved on it. There is usual stuff such as water resistance (which is 300 meters by the way, and that’s ISO certified) or serial number. However, there is also calendar engraved on the caseback with noted approximately date of next battery change. Pretty useful.
Another interesting fact about the case is the use of special L shaped gasket under the caseback.
It serves as helium escape valve, which means in will release excessive helium from the case during saturation diving. I stand corrected, instead of releasing helium, L-shaped gasket significantly reduces the chance of He getting to the case in the first place, thank you It also ensures 300 m water resistance.
The case has polished finishing, which includes lugs and caseback. However, it’s barely visible because almost entire case is protected by a stainless still shroud. The shroud is probably the most distinctive feature of the watch, as well as the wole Seiko Tuna lineup. This feature become so iconic that various microbrands try to attract potential customers with their shrouded-style divers, such as Regia Diver, recently featured on the blog . The shroud of Seiko SBBN015 is fitted with three hex screw and has a nice brushed surface. Originally, its main purpose was to absorb any shocks that your watch could encounter during diving. However, it still looks cool are really tool-like, and lets be honest here, to me it is its main purpose. It doesn’t mean you should be afraid taking a Tuna for diving, it’s still a very capable diver’s watch, which will feel right at home in any water scenario. The shroud has proven to serve also another purpose. Over the years of wearing, it tanked all the scratches I could threw at the watch. When I decide to service my Tuna one day, it’s going to be really easy to buff the scratches off the shroud to make it look brand new.
Seiko SBBN015 is a diver’s watches, which means there has to be a diving bezel on board. It’s 120 click bezel, which is protected by the protruding shroud. There are two cut-offs on the shroud on the opposing sides to allow a firm grip. Indeed, it works great as the grip is very secure and the bezel is easy enough to turn even with wet hands. The bezel insert is black DLC coated steel, which makes it much more durable than usual aluminium inserts. There is full 60 minute scale on the bezel to allow an accurate time measure. At 12 o’clock there is a lume pip which is highly visible in low light situations.
Dial, hands, crystal
The dial on Seiko TUNA SBBN015 is a classic one. Its layout was used on a few models before it, be it a SBBN007 or a golden 7549-7009 Tuna. However, there were some improvements made here and there. There are still flat hour markers generously filled in with Seiko lume . This thing glows in the dark like a torch. At 3 o’clock there a day-date window with a nice silver printed frame. Seiko SBBN015 being a watch created for the Japanese domestic market has a day wheel printed in Kanji, which I find really cool. Of course, there is also English option available.
I wanted to point out one more thing about SBBN015 style handset and its looks. It’s a characteristic feature of Seiko Tuna lineup, something like mercedes-style hands for Rolex Submariner. However, for unknown to me reason Seiko decided to change these hands in their latest generation of quartz Tunas (i.e. SBBN031). You don’t do it Seiko, you just don’t do it
On of the most important changes in regard to the previous generation of Tuna watches, is the fact that SBBN015 was moved to a higher tier of watches and now it’s a part of Seiko Marinemaster series next to i.e. Seiko Marinemaster 300 SBDX001. To represent that change, SBBN015 has “MARINEMASTER PROFESSIONAL” name printed at 6 o’clock on the dial. The Seiko logo has also been improved and now it’s an applied brushed metal instead of simple printing. It’s a great choice and adds some needed sophistication to this otherwise very tool-oriented timepiece.
I love the handset of this watch. Again, it’s a design that has been used before but why change something if it works? The hour and minute hands are flat but they have a nice brushed finishing, which gives them really interesting, industrial look. Similarly to hour markers on the dial, Tuna handset has been generously filled with Seiko lume to provide plenty of light in low light situations.
I wanted to point out one more thing about SBBN015 style handset and its looks. It’s a characteristic feature of Seiko Tuna lineup, something like mercedes-style hands for Rolex Submariner. However, for unknown to me reason Seiko decided to change these hands in their latest generation of quartz Tunas (i.e. SBBN031). You don’t do it Seiko, you just don’t do it. At least not as dramatically.
Seiko SBBN015 is using a double domed Seiko Hardlex crystal. It’s a great looking crystal, which is extremely shatter resistant. That’s why it was chose for this tool watch. I’m usually ok with Hardlex but my piece got a few scratches here and there, probably because of the high dome. Personally, I would rather see a sapphire crystal and I believe many people agree with me on this. I’ve seen numerous photos of moded Tunas with a nice blue-tinted sapphire crystals. It would be great if it was a stock option designed by Seiko itself.
Yup, it’s quartz and there is no smooth sweeping second hand. I know it will put many people off but that’s how the things are. Seiko SBBN015 runs on a 7C46 quartz movement designed especially for Tuna lineup. It’s a fully metal construction fitted multiple jewels to ensure reliability for many years. It’s also hi-torque movement, meaning it’s extremely power sufficient. An average battery life-time is 5 years! Fans of accuracy might be not pleased either because 7C46 is rated to +/-15 s a month. As I mentioned before, this movement is a reminiscent of Seiko ideology from the 1970’s where usability was put over form.
I know that it might be rose-tinted glasses speaking but there is something about this watch that made me actually enjoy quartz movements. Before SBBN015 I would rather avoid quartz watches altogether. However, when I spent some time with it I actually came to like it and appreciate its robustness. If I were to take one watch to a deserted island, it would be quartz Seiko Tuna because I’m sure it wouldn’t let me down in any scenario.
Straps and wearability
Seiko SBBN015 Tuna comes on a stainless steel bracelet. It’s actually pretty decent bracelet, which is 22 mm wide at the lugs side and tapers down 18 mm. This generous taper makes the watch really comfortable on the wrist. To add even more comfort, the bracelet has been fitted with Seiko Marinemaster ratcheting clasp which is easily adjustable. You can use it to put over a swim suit or simply expand the bracelet slightly during a hot day for an increased comfort. There is one issue with the claps though. It’s made of mix of stainless steel and titanium, which made it a scratch magnet. Mine is scratched unlike any other watch I owned and wore for similar time. However, these scratches are not really deep and are probably quite easy to get rid.
I mentioned that you would appreciate the drilled lug holes on this watch and that’s certainly true. Seiko SBBN015 looks perfect almost on everything. It goes great with nato straps, rubber straps, or even leather. On of my favourite combos is Isofrane or Universal Crafterblue rubber strap. It feels like these two were meant to be worn together.
Seiko Tuna SBBN015 is a bulky sports watch and surely you won’t wear it in any formal situation, unfortunately there is no way around it. However, it will do just fine as a daily driver. It’s really comfortable on it’s stock bracelet or on a leather strap if you decide to dress it up a bit. The 48 mm lug to lug length make it ideal everyday watch and at this point I can’t imagine my collection without it.
Seiko TUNA SBBN015 is an extraordinary timepiece. It combines all the best aspects of the real tool watch designed to have the job done with a slightly more modern approach. I love it’s robustness, historical dial, beautiful brushed handset, and reliable 7c46 quartz movement. I love the unique look that no other dive watch on the market has. There is very little to dislike about the watch either. Some may argue about the fact that the movement is quartz and not automatic, perhaps Seiko could have chosen a sapphire crystal instead of domed Hardlex. However, to me it’s almost a perfect dive watch and probably the best diver Seiko has ever released. I even value it over Marinemaster 300 SBDX001 since I find Tuna to be much more unique. And remember MM300 is at least twice the price of SBBN015, if you happen to find one on the market as it has been discontinued and replaced by new generation of quartz Tunas. I hope it speaks for itself. Keep in mind that’s my subjective opinion and yours is likely to differ, and that’s fine. Let me know what do you think is the best Seiko diver ever released.
+ unique design
+ great built quality
+ robust quartz movement
+ extremely comfortable
– perhaps it could use a sapphire crystal
– SBBN015 has been discontinued
|Lug to Lug||48 mm|
|Lug width||22 mm|
|Crystal||Double domed Hardlex|
|Movement||Quartz 7c46, 5 years of power reserve|
|Water resistance||300 m ISO certified|
Seiko TUNA SBBN015 is an extraordinary timepiece. It combines all the best aspects of the real tool watch designed to have the job done with a slightly more modern approach. I love it's robustness, historical dial, beautiful brushed handset, and reliable 7c46 quartz movement. I love the unique look that no other dive watch on the market has. There is very little to dislike about the watch either. Some may argue about the fact that the movement is quartz and not automatic, perhaps Seiko could have chosen a sapphire crystal instead of domed Hardlex. However, to me it's almost a perfect dive watch and probably the best diver Seiko has ever released. I even value it over Marinemaster 300 SBDX001 since I find Tuna to be much more unique. And remember MM300 is at least twice the price of SBBN015, if you happen to find one on the market as it has been discontinued and replaced by new generation of quartz Tunas. I hope it speaks for itself. Keep in mind that's my subjective opinion and yours is likely to differ, and that's fine. Let me know what do you think is the best Seiko diver ever released.