Seiko Sea Urchin: A Review of Seiko’s Heavyweight in the Diving Arena

Seiko Monster, Seiko Tuna, Seiko Turtle, Seiko Sumo — ask any newbie or expert watch collector about these names, and they will almost definitely recognize them. That is because they are all popular dive watches known for showcasing Seiko’s true value. They are proof of the brand’s expertise in producing high-caliber yet reasonably-priced timepieces. All of these affordable dive watches by Seiko have been adored by watch enthusiasts across the globe for years.

However, in this article, we will not be looking at any of the aforementioned dive watches, many of whom have already been subject to much discussion. Instead, we will be delving a little deeper into another affordable, underrated dive watch that completes Seiko’s lineup of divers: the Seiko Sea Urchin. Hailing from the brand’s Seiko 5 range, the Seiko Sea Urchin is a sleek and well-built dive watch, with a classic design that is reminiscent of the Rolex GMT-Master II Ref. 126710blro-0001. So, without further ado, let us take a closer look at the most popular Sea Urchin watch, the Seiko Sea Urchin SNZF15, and everything it has to offer.

First Impressions

Right off the bat, you will find that the Seiko Sea Urchin SNZF15 bears a very quintessential design that harkens back to two famous Rolex pieces: the Rolex Submariner and the Rolex GMT-Master II. While its easy-to-read dial layout closely resembles that of the Submariner, the Seiko Sea Urchin’s stylish colorway and overall design is a definite callback to the Rolex GMT-Master II Ref. 126710blro-0001. This classic aesthetic is a large part of why the Sea Urchin SNFZ15 is the most popular of the Seiko Sea Urchin timepieces.

As a dive watch, the Seiko Sea Urchin is not quite on par with the Rolex Submariner. Nevertheless, with its well-polished finish and durable build, this is a great diver watch and an excellent, affordable alternative to the Submariner. If you are looking for your next dive watch, but you are working with a limited budget, then the Seiko Sea Urchin SNZF15 is definitely an option you should keep in mind.

Anatomy of the Seiko Sea Urchin SNFZ15

front view of Seiko Sea Urchin SNZF15  watch
Image by Amazon

Case and Caseback

The Seiko Sea Urchin SNFZ15 comes in a 41mm stainless steel case, which is very resistant to scratches and impacts. It has a rather standard case diameter, which enables this watch to fit well on wrists of virtually any size. Furthermore, its angular, finely beveled lugs add to the impression of slimness, making this watch look a little smaller than it actually is. It also has a thickness of just 13mm, making this quite a slender dive watch. Altogether, this is a very comfortable and easy-to-wear dive accessory and you should have no trouble toting the Seiko Sea Urchin around on your wrist all day.

The sides of the Seiko Sea Urchin’s case are well-polished, giving it a gleaming and highly-reflective lustre. This is contrasted against the brushed, satin-finished lugs, which look sleeker and a little more subdued. This interplay of alternately brushed and polished surfaces makes the Seiko Sea Urchin look incredibly sophisticated and luxurious. Every inch of this watch plays with the light expertly, which is what makes it so pleasing to look at from various angles.

On the underside of the Seiko Sea Urchin, you can find a see-through caseback made of Hardlex crystal. This allows you to freely view the beauty of the movement that beats inside the watch. This is a classic feature that any watch connoisseur would surely appreciate. A mid-sized crown is also located on the right side of the case, at 3 o’clock. Protected by short crown guards, this crown has gear-like edges which provide wearers with a better grip, so they can grasp and turn the crown more easily, even in their diving suits.

Bezel and Dial

dial of Seiko Sea Urchin SNZF15  watch
Image by eBay

As a dive watch, the Seiko Sea Urchin SNFZ15 comes with a unidirectional elapsed time scale bezel, which enables divers to safely keep track of how much time they have spent underwater. The bezel of the Seiko Sea Urchin is crafted from stainless steel, with distinctive edges that almost look like the sides of a bottle cap. It is also fitted with a glossy elapsed time scale insert made of ceramic, which is highly scratch-resistant. This insert comes in gorgeous red and blue Pepsi colors. It is this stylish bezel that gives the Seiko Sea Urchin its resemblance to the famous Rolex GMT-Master II Ref. 126710blro-0001, otherwise known as the Rolex Pepsi.

The dial of this watch comes in matte black, contrasting against the vibrant, Pepsi-colored bezel. It follows a very straightforward layout that recalls the simple dial design of the Rolex Submariner. The Seiko Sea Urchin’s dial comprises hour indices in various geometric shapes and thick sword-shaped hands. At 3 o’clock, you can find an elongated day-date aperture, outlined in silver to stand out more strongly against the black backdrop. The hands and indices are all generously coated in lume, which glows a bright, neon blue in the dark, allowing for optimal legibility even in poor lighting conditions.

Seiko has also outfitted this watch with an elevated chapter ring, which is located on the rim of the dial. This chapter ring comes in jet-black to match the dial and bears markers in white for the minute track.


One of the best things about the Seiko Sea Urchin SNFZ15 is the robust in-house caliber that runs inside. This watch is driven by the Seiko Caliber 7S36, first released in 1996. This movement is held together by 23 jewels and beats at a frequency of 21,600 vibrations per hour. It also possesses a power reserve of 41 hours, so you can leave the Seiko Sea Urchin aside for more than a day without having to worry about winding or resetting it.

An unexpected delight about the Caliber 7S36 is that, despite being fairly affordable, this movement actually has a remarkable accuracy rate. Wearers have reported that properly calibrated Caliber 7S36 can reach precision rates of +/-2 seconds per day. In other words, this powerful movement can achieve timekeeping precision well beyond what other more expensive calibers are capable of. With the Caliber 7S36, you can rest assured that your Seiko Sea Urchin piece will give you impeccable timekeeping and reliability.


To complete the watch’s sleek look, the Seiko Sea Urchin SNFZ15 is paired with a three-link stainless steel bracelet. It measures 22mm in size, with removable end links so you can adjust the strap to better fit around your wrist. It also has a triple-lock clasp, which ensures that the strap stays securely fastened to you, even when you are diving.

If you are not a fan of steel bracelets, Seiko also offers wearers a NATO-style strap as a second option. The NATO strap is perfect for wearers who want to wear their Seiko Sea Urchin as a simple piece to complement their daily outfits. However, while the NATO textile strap is very comfortable, it is not recommended for frequent divers. This is because it is not waterproof. As such, for dedicated divers, the stainless steel bracelet is still a better alternative that delivers more comfort on diving adventures.

Water Resistance

As a dive watch, the Seiko Sea Urchin SNFZ15 has a depth rating of 100 meters. This is quite a typical water resistance capacity for a regular dive watch, especially for one as affordable as the Seiko Sea Urchin. While it is more than enough for your next swim or snorkeling expedition, it is not quite enough for any deepsea scuba diving adventures you might have planned.


As we have mentioned, the Seiko Sea Urchin is known for being a very affordable diver, even amongst the ranks of Seiko dive watches. The Seiko Sea Urchin SNFZ15, in particular, sells at just $255 USD. This is a very budget-friendly price considering the Sea Urchin’s classy stylishness and robust timekeeping.

Alternatives to the Seiko Sea Urchin

It cannot be denied that Seiko did an excellent job designing the Seiko Sea Urchin. It is a robust and classy dive watch that is easily considered top-of-the-line in its price range. That said, it might not be to everyone’s tastes. Maybe you want a dive watch with a better water resistance capacity, or you want something that looks and feels more high-end. If so, fear not! We have curated a list of the three best alternatives to the Seiko Sea Urchin that you can check out below.

1. Mido Ocean Star Ref. M026.627.44.041.00

front view of Mido Ocean Star  M026.627.44.041.00 watch

The first watch on this list is the Mido Ocean Star Ref. M026.627.44.041.00. This is a sporty, suave-looking dive watch with an excellent build and impressive features. It is presented in a 44mm titanium case coupled with a matching three-link titanium bracelet. Although this watch is slightly bigger than the Seiko Sea Urchin SNFZ15, it is actually easier to handle and carry about all day, thanks to its lightweight and hypoallergenic titanium build. Fixed on top of the case is a unidirectional rotating bezel with a deep blue elapsed time scale insert made of aluminum.

Mido complements the watch’s bezel with a striking, sea-blue dial. As opposed to the simpler, easier-to-read dial of the Seiko Sea Urchin, the Mido Ocean Star Ref. M026.627.44.041.00’s dial is packed full of handy complications. It comprises rectangular hour indices, luminous, hollowed-out hands, and a long date window at 6 o’clock. It also follows a chronograph layout, with two sub-dials for the 30-minute and 60-second counters. On the rim of the dial, you can find a chapter ring with white markers for the nautical tachymeter, a useful and unique function not frequently seen in dive watches.

Driving this Mido Ocean Star diver is a powerful in-house Caliber 60. This movement is modified from a base ETA A05.H31 caliber. The Mido Caliber 60 also manages to outdo the Seiko Sea Urchin with its 60-hour power supply and substantial 200-meter depth rating.

The Mido Ocean Star Ref. M026.627.44.041.00 is available at approximately $2,019 USD.

2. TAG Heuer Aquaracer Ref. WBP201C.BA0632

front view of TAG HEUER Aquaracer WBP201C.BA0632 watch

If you are into minimalist aesthetics, then the TAG Heuer Aquaracer Ref. WBP201C.BA0632 should be right up your alley. This diver timepiece utilizes a 43mm stainless steel case and a three-link stainless steel bracelet. Its sleek all-silver exterior is contrasted against a jet-black elapsed time scale bezel. This bezel comes in an unusual dodecagon shape, with slightly angular sides that give this watch face a bit of an edge. On the right side of the case, you can find a sizeable screw-down crown protected by short crown guards on either side.

The dial of this TAG Heuer watch comes in a clean white hue that blends well with the monochrome look of the rest of the watch. It bears a pattern of horizontal teak lines which resemble the flooring of yachts, calling back to its dive watch status. This dial is very straightforward, consisting of just geometric hour indices and sword-shaped hands outlined in silver, along with a magnified date aperture at 6 o’clock. A long seconds hand with a vibrant yellow tip serves to add a splash of color to this watch face. The hands and indices of this watch have been treated with neon green and blue lume, which helps illuminate the watch’s face in the dark.

This TAG Heuer Aquaracer piece is run by a reliable TAG Heuer Caliber 5. This in-house automatic movement delivers a 38-hour power reserve and a whopping 300-meter water resistance capacity, which triples the depth rating of the Seiko Sea Urchin. If you want a robust dive watch capable of surviving extreme conditions deep underwater, then this TAG Heuer Aquaracer Ref. WBP201C.BA0632 is definitely worth considering.

This watch sells at around $2,849 USD.

3. Rolex Submariner Ref. 124060-0001

front view of Rolex Submariner 124060-0001 watch

A list of Seiko Sea Urchin alternatives would not be complete without a Rolex Submariner piece. In this entry, we are looking at the Rolex Submariner Ref. 124060-0001. With its extremely similar dial layout and professional look, this is a high-end, luxury alternative to the Seiko Sea Urchin.

This Rolex Submariner piece is housed in a 41mm Oystersteel case and matching three-link Oystersteel bracelet, which is extremely resistant to scratches, shocks, and impacts. This lustrous, silver exterior is sharply contrasted against a classic black dial and bezel. The bezel of this watch is also made of Oystersteel and is fitted with a top-of-the-line Cerachrom elapsed time scale insert. The black dial, meanwhile, contains just hour indices in different geometric shapes and Rolex’s signature Mercedes hands. As is typical for dive watches, the hands and markers of the watch are all coated in lume for optimal legibility even in low-light settings.

Inside this Rolex watch, you can find a top-notch Rolex Caliber 3230. This in-house automatic movement is very robust and is able to withstand strong magnetic fields and shocks. In addition, it guarantees an extended 70-hour power supply and has an outstanding 300-meter depth rating. Finally, this Rolex caliber is incredibly precise, with an accuracy of +/-2 seconds per day, matching the precision of the Seiko Sea Urchin.

Prepare to shell out around $16,599 USD for this top-tier diver.

Final Thoughts

On the whole, the Seiko Sea Urchin is an incredibly well-built dive watch, especially considering its affordable price. On top of its hardy build, this timepiece also comes with a stylish Pepsi design that is more commonly seen in GMT watches than dive pieces. Inspired by the Rolex Submariner, the Seiko Sea Urchin is a great, budget-friendly choice for an entry-level dive watch you can take underwater.

All images are credited to unless otherwise stated.

Can’t get enough with the powerful and robust Seiko watches? Have some time to read our article about the 10 Best Seiko Chronograph Watches.

Featured image courtesy of u/henryd1214 on Reddit.

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