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Seiko Prospex SUN023 Review



Today we look at the Seiko Prospex SUN023, the kinetic GMT dive watch. This watch combines a number of useful features like a movement that's powered by the motion of your wrist and a GMT complication, but its most prominent attribute is its wild looks. A bright orange bezel with blue and orange hands really set it off and will get this watch plenty of attention. Behind the good looks, however, is a serious diver's watch ready for almost anything you can throw it.

The Introduction



Seiko Prospex watches can be traced back to the very first Seiko dive watch released back in 1965, which featured a then-astonishing 150 meters of water resistance. This watch formed the foundation of modern Japanese dive watches, but it wasn't until 1975 that Seiko released their first "professional" dive watch, the watch from which Prospex (professional specifications) ultimately derives its lineage. That watch featured a still-impressive 600 meters of water resistance, titanium construction, new helium protection for saturation divers and improved shock resistance. Perhaps even more importantly, it featured many of the design elements that we now associate with Seiko divers--the accordion strap and the tuna case.



Fast forward to 2014, when this SUN023 was released, and we can see a lot of that heritage here--mainly in the case, bezel and strap designs. Like its predecessors, it features outrageous amounts of lume and supreme legibility. Yet it's also thoroughly modern, with a kinetic movement, which is basically a quartz movement with an electrical generator powered by your natural motion--an automatic quartz, if you will. The GMT hand is quite probably inspired by Seiko's super high tech Spacewalk's GMT hand.

The Face



The face looks great. Divers can easily become too serious or "hardcore" when it comes to face and hand design--this is not the case of the SUN023. Brightly colored hands and writing on the bezel give it a playful side and keep the watch from falling into the sea of sameness that so plagues the dive watch world.



The dial has an incredible amount of depth, thanks to its four hands on a single axis and super tall hour markers as well as a chapter ring that is placed above, instead of beside, those hour markers.



The matte black dial contrasts really well against the bold hands and markers.



Speaking of hands, the Prospex SUN023 has four of them. Orange is the minute hand, steel the hours and blue the GMT. You'll also notice the popular lollipop seconds hand design, yet another feature associated with Seiko diver heritage. The color coded nature of the watch, against the black backdrop, and the size of the hands, makes it extremely easy to read, even at night when the lume takes over.



The GMT hand is skeletonized in order to make it easily distinguishable at night when lume takes over. I'm confident this blue GMT hand is inspired by the Seiko Spacewalk's GMT hand. Moreover, note how the entire dial is color coded, not just the hands. The GMT numerals are in matching blue, the cardinal hour markers are in silver paint and the orange minutes hand is matched to the orange rotating bezel. And yes, the GMT hand is fully independent, with extremely well defined "clicks" for each hour. This is also how you set the date forward or backward on the SUN023.



The date is quite subtle, placed between the 4:00 and 5:00 markers. Divers will often use this half-way approach so that it doesn't get in the way of any lume. It's just a simple cutout, but the matte black texture of the date ring and dial match so well you really can't see the edge anyway.



The lume is absolutely phenomenal and well thought out. It's impressively even, particularly for this price range and just astonishingly bright. Also notice its clever design--the hands look nothing alike, particularly the irrelevant (while diving) GMT hand. The seconds hand is a lollipop so there's no way you'll get that confused. Also note that the 12:00 marker is very distinct from the other cardinal markers, making this easy to orient even in the dark. Fans of lume are going to love this one.

The Case



The 47.5mm case is quite large, but the watch wears a little smaller than you'd think thanks to the relatively small dial. Although it's a big watch, it's in line with contemporary diver standards in terms of size.



The case is styled after the famous Tuna with a large shroud that protects the watch underneath. Only one part of the edge of the bezel is exposed on each side, making it more difficult to knock around while diving and also offering extra protection. The shroud itself, as opposed to the exposed stainless steel case, is black coated. Like the Spring Drive Tuna, the black coating still looks very metallic and has a brushed finish--it looks like really dark steel, not like the coatings you'd find on most watches. I can't confirm this, but I suspect it's a titanium nitride treatment, which in my experience has been one of the more scratch resistant ways to black coat metal.



One of the coolest features on this watch is its bright orange unidirectional bezel. The orange is really bright and has a metallic shimmer to it. The feeling of the bezel is mostly typical of Seiko with really smooth rotation, but I would prefer to see a little more definition in the detents. It's very easy to glide over the particular spot you want because the detents don't offer much resistance.



One of the coolest things about the case is that the shroud is skeletonized on each side, showing the shiny steel case underneath. Very cool look.



The huge crown (unnecessarily huge, I might add, since it's a kinetic and doesn't need to be wound) screws down for a 200 meter water resistance rating, plenty for virtually everyone. At first glance you'd think that other "crown" might be a helium escape valve, but it's actually the power reserve indicator. Seiko eliminated the need for helium escape valves, even on their most water resistant divers, by using specially designed seals called L gaskets.



Interestingly, even the power reserve pusher is screwed down. To use it, just unscrew and press the button down. The seconds hand will race ahead and how far it advances tells you how much energy remains stored in the watch. A very handy feature. Of course, if you wear it every day, you could conceivably go a decade or longer without it ever dying thanks to the kinetic technology. As an aside, I really like the little orange stripe they put on the crown.



Naturally, being a quartz/kinetic watch, there's no movement to look at, so the case back takes the traditional diver approach and uses a full polished steel piece that looks great.



The back is nicely made though with a great high polish finish and a tidal wave logo in relief.

The Movement



The movement is a 5M85 kinetic GMT. As I mentioned earlier, kinetic refers to Seiko's hybrid automatic/quartz technology. Your movement actually powers an electric generator and that power is stored in a battery (no longer a capacitor). This means that the kinetic, unlike the spring drive, shares a lot in common with a good quartz movement.



Kinetic is a good fit for a diver since this is going to be a high activity sports watch. Still, don't think that the power reserve works like your mechanical watch--fully "wound" (charged), the 5M85 has a six month power reserve, so you really don't have to give it very much attention to keep it running. Of course, quartz movements in general are inherently tougher and more accurate than mechanical movements as well, so you can be a little more rough with this watch than you might want to be with one of the automatic Prospexes.



As I mentioned before, the blue GMT hand is truly independent and it has a terrific feeling with very clear clicks into each hour position. Being a GMT watch, it lacks a quickset date, but that's easily remedied by the independent hour hand which can set the date forward and backward quite quickly.

The Video

See our high definition video here: https://www.youtube.com/watch?v=oA9j80-E8u4

The Conclusion



I see the SUN023 as a much more affordable, more playful alternative to the hit Spring Drive Tuna SBDB009. As amazing as the spring drive is, this SUN023 should be close to its accuracy and is still powered by your wrist, all for a fraction of the price.



It's also a good showcase for functional design. The colorful hands may be cool to look at, but their shapes, lume and coloration are all intended to increase legibility. The replaceable shroud means that your case is much less likely to get beaten up. The accordion strap will stay super comfortable even in widely varying temperatures and over a wetsuit.



It's no surprise, then, that this is one of the most popular Prospex watches so far. On top of the functionality, it just looks very, very cool and has a lot of the charm of the SBDB009 at about 1/6th the price, meaning that this is a dive watch you might actually go diving in.
 

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Thanks for the great review, stunning watch, i got the SUN019 all stainless model a bit over a week ago.
Simply stunning, unique, perfect size on my 7.5'' wrist, an epic deep 3d dial, bezel is nice and tight, not too heavy, its a beautiful watch but still looks like it means business.
I find it modern with retro roots, you can see a few vintage seikos like the turtle in this one.

For anybody that likes bigger divers, i highly recommend one of these, the pics dont do them justice.
I personally think the all stainless sun019 shows off the design best, its my fav of the bunch but this ones lovely too.
And as it says you could swap the shrouds to go black or SS.

Im not a kinetic fan, but this one has a full 6 month charge after a weeks wearing on and off, so seikos kinetics are getting more refined id guess.

cheers and thanks for the review TLW.
 

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Brightly colored hands and writing on the bezel give it a playful side and keep the watch from falling into the sea of sameness that so plagues the dive watch world.
This is so true and couldn't put it better myself! Hence my sudden recent urge for orange and now I've gone back to black but with some blue added. I need some colour in my watch world!

Looking forward to the next review.​
:13:​
 

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Any reason why the lume of the second hand is only on the end side of the hand? It does however provide a 30 second gap with actual running time, if used during a dive - but highly unlikely to be the basis when diving.
 

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Any reason why the lume of the second hand is only on the end side of the hand? It does however provide a 30 second gap with actual running time, if used during a dive - but highly unlikely to be the basis when diving.
There are a lot of theories as to the origin or popularity of the lollipop seconds hand which is closely associated with dive watches. The theory I've found most appealing is that it made the dial clearer to read under water because the seconds hand was effectively much shorter than the hour or minute hands. If you've got an Aqua Terra 8500, for instance, the seconds hand lume closely resembles the minute hand at night, so at a glance, it can be slightly more confusing.
 

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There are a lot of theories as to the origin or popularity of the lollipop seconds hand which is closely associated with dive watches. The theory I've found most appealing is that it made the dial clearer to read under water because the seconds hand was effectively much shorter than the hour or minute hands. If you've got an Aqua Terra 8500, for instance, the seconds hand lume closely resembles the minute hand at night, so at a glance, it can be slightly more confusing.
I believe its part of the ISO standard for dive watches to have an indicator that the watch is running.

The second hand itself would be of no use whilst diving.

Other John
 

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Nice review. Thanks for taking the time for wonderful pictures also.
 
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