The ULTIMATE Guide to Seiko Mini Turtle Models (2024 Updated)
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seiko mini turtle

The ULTIMATE Guide to Seiko Mini Turtle Models (2024 Updated)

Here at Exquisite Timepieces, we like the groovier things in life, like premium timepieces characterized by excellent craftsmanship. It’s no news that Seiko is among the world’s most prestigious and value-driven watch brands. Ask any watch lover, aficionado, collector, or even a diver to describe Seiko in two words, and your answer will certainly be a variant of the phrase; Terrific Value! 

From the Prospex line (made up of sport/tool watches) to the Presage line (made up of dress/retro timepieces), the brand’s catalog is massive and modestly priced. This is especially true of the Seiko SRP series, a reinterpretation of the brand’s 6309-series divers, nicknamed Turtle by Seiko’s fandom.

A collection marked by highly functional tool watches for the commoner that hogged the limelight with its cushion-cased design. Though a massive hit upon its release, the SRP77x did not sit well with many collectors as most found the large case size too substantial for their wrists leading to the release of the Mini Turtle a year later.

About the Seiko Mini Turtle

Towards the end of 2017, Seiko officially announced the release of three small Turtle variants. They were the SRPC35K1, SRPC39K1, and SRPC41K1, all of which are divers. Most people leave the count at four (including the SRPC37K1), but the SRPC35K1 and SRPC37K1 are essentially indistinguishable, save for the fitted straps.

The SRPC35K1 features a stainless steel bracelet, while the SRPC37K1 comes mounted on a two-piece silicone band. Originally intended for the dreaded Japanese Domestic Market, Seiko took a turn and made these watches available across the globe as well due to the high interest.

The nickname “Mini Turtle” was given to the trio by Seikodom. This was because of their oval case that resembled a turtle’s shell – a stark similitude to watches in the SRP series. The SRP series was a reinterpretation of Seiko’s third generation of professional divers (the venerable Seiko 6309) and featured mid-level divers.

Enthralled by the resurgence of the Seiko Cult Classic, collectors and enthusiasts made a run for the Turtle. However, the comparatively large case diameter didn’t sit well with many people, leading to the peculiar Mini Turtle/SRPC model release. 

The Mini Turtle, which lives in the Prospex (or Professional Specifications collection), is solidly built for use in the professional world. Being a dive watch, and a retro one at that, the Mini Turtles are great for regular people who loved the design of the regular Turtle models but balked at the size and longed for a scaled-down version. All variants are reliable watches best suited for casual or business-casual wear.

These stainless steel timepieces all run counter to their bulkier counterparts regarding size, dial design, and crown position at 3 o’clock. The case size is now 42.3mm (a 2mm drop from its predecessors), and the 4R36 automatic in-house caliber has now been replaced with the 4R35. In lieu of the day/date display at 3 o’clock is a date complication with a magnifying glass on the Hardlex crystal.

For their looks, the SRPC39K1 flaunts a matte blue dial and blue bezel. The SRPC35K1 (& SRPC37K1) has a black dial and bezel, while the SRPC41K1 (developed primarily for divers) is co-branded with PADI (Professional Association of Diving Instructors) and features a wavy black dial with Pepsi-style bezel and red minute hands. 

In summary, when compared to Its predecessor, the five most notable changes that can be observed are: smaller dimensions, relocation of the crown, elimination of the day complication, addition of the magnifying glass, and use of the 4R35 caliber movement.

Seiko Mini Turtle History & Origin

Since the release of Seiko’s (and Japan’s) first dive watch (the 62MAS-010) in July 1965, the brand has continued to introduce divers that topple the Swiss watch industry earning itself a top spot in the world of watchmaking. 

Seiko’s invasion of the world of divers has been innovative, and the SRP collection is one of such outstanding inventions. The line boasts a historic design that continues to charm collectors and enthusiasts alike with its warm retro vibes.

Coming as a reinterpretation of Seiko’s third generation of professional divers (the venerable 6309), the roots of the present-day Seiko Turtle stretch back to 1976 with the debut of the 6306 and 6309 models. The ref. 6306-7000/1 was released for the Japanese Domestic Market only, while the 6309-7040/9 was the worldwide version.

Modeled by Seiko’s master watch designer, Ikuo Tokunaga, the collection was a follow-up model to the ref. 6105, the very first cushion-shaped case watch from Seiko

However, unlike the ref. 6105, the 6306, and 6309 models were dubbed ‘Seiko Turtle’ because they were considerably more globular and symmetrical. The timepieces came with a smooth-edged case that protruded on both sides of its crown, giving them the appearance of a turtle’s shell when viewed from above.

With a depth rating of 150 meters, the 6306 and 6309 references offered extraordinary durability that could satisfy any recreational diver’s demands and be used for decades without worrying about servicing. With a diameter of 45mm, the watch might have been overly big then, but the cushioned case and crown at 4 o’clock made it surprisingly comfortable on the wrist.

Even though the JDM models were more alluring (and expensive) since they featured more jewels, hacking movement, and an English/Kanji day-date wheel, the ref. 6309 largely ruled Seiko’s entry-level diver’s segment until 1988, when the line was discontinued.

To the ecstasy of vintage Seiko connoisseurs, the brand re-launched the SRP series in the Prospex line in 2016 after over 20 years of dormancy. The new Turtle models were nearly identical to the 6309 models and featured the historic trait of the Turtle line; a cushion-shaped oval case and a crown at the 4 o’clock position, but now had an upgraded water resistance rating of 200 meters.

With a case size of 44.3 mm (the “King Turtle” variants measure 45 mm), the new Turtles were a bit cumbersome for people with smaller wrists, leading to a downscale version/three smaller variants measuring 42.3 mm in diameter. The new variants were instantly dubbed Mini Turtle since they were smaller, more compact, sleek, and elegant, giving everyone a chance to strap on a piece of history.

Seiko Mini Turtle Review


Like its predecessors, the Mini Turtle sports a cushion-shaped, oval case. The 316L stainless steel case measures 42.3mm in diameter and has beautifully curved, polished sides with a very high mirror finish. 

For the height, it is 13mm thick, with nice 22mm lugs that are detached from the flange revealing the attachment between the bezel and mid-case where the strap passes through. 

Unlike its predecessors, all the versions of the Mini Turtle have unguarded crowns at 3 o’clock (rather than 4), which screw down firmly for excellent water resistance. Even though some dive watch enthusiasts consider the position of the crown a downside, it works great. 

The top of the case features a consistent circular brushing giving it a sunburst sheen, while the case back has the standard Katsushika Great Wave by Hokusai etched in the middle. In addition, you’ll find the Prospex logo, Diver’s Watch 200m, Stainless Steel, and 4R35 inscribed around the edges of the case back.


The dial is everything you’d expect from Seiko; clean, ultra-legible, highly contrasting with precise execution of all the details. 

The Turtle’s emblematic look, which has demonstrated its effectiveness for decades, can be recognized instantly. Even though the layout of the dial is relatively unchanged from earlier iterations of the Mini Turtle, the polished steel applied indices for the Mini-turtle are exclusive only to its variants. 

Rather than the regular printed or applied circular indices with some form of a triangle at the 12 o’clock position, the Mini Turtles’ are somewhat rectangular with rounded ends and syringe extension markers at all the cardinal points (6,9, and 12 positions).

Like most Seiko divers, the dials feature a charmingly minimalistic and elegant look with well-executed lettering. SEIKO can be seen at the 12 o’clock position, and right down at 6 o’clock is the Prospex “X” logo, followed by the words AUTOMATIC and DIVER’S 200m beneath the logo.

Again the words ‘Made in Japan’ can be seen across the edge of the dial, flaunting the noble quality and superiority of the timepiece. The brilliantly new textured dials are all about legibility and feature an insane amount of Seiko’s famed proprietary LumiBrite lume, applied generously on the hands and indices.

Unlike its predecessor, the day/date display at three has been given up for a simple date display with circular cyclops for ease of reading.

Size and Proportions

The size and proportions of the Mini Turtles are where a major change from its predecessor has occurred. The core of the case design has not changed, but it has gained a more defined shape, with curves and flow, getting rid of the bulky feel the previous models had.

The diameter is now 42.3mm though it used to be 44mm to 45mm in the past generations; thus, a 2mm decrease compared to previous Turtles. The thickness has remained at the same level (13 mm), and the lug-to-lug measurement is at 43mm – which is thinner than its predecessor’s and very compact for its size, making the Mini Turtle suitable for most wrists.

It weighs approximately 154 grams, roughly 40 grams less than the weight of the Turtle SRP77x on a bracelet, so it can be worn for several hours without a bulky feel.


The Mini Turtle is equipped with the 4R35 caliber movement, a remarkable upgrade from the popular 7S26 movement, which did not offer the expedient hacking and hand-winding function. Beating at 21,600 vibrations per hour, the Seiko’s in-house caliber 4R35 automatic movement contains 23 jewels and features a power reserve of approximately 40 hours.

The elevated quality of the Mini Turtle transcends beyond aesthetics to mechanical properties, as the 4R35 boasts noteworthy robustness from Seiko’s Diashock anti-shock system. The proprietary Diashock technique entails a spring-loaded mounting system that supports the balance wheel and absorbs impact, keeping the timepiece highly accurate and reliable for decades. Overall the mid-tier movement is solid, has an accuracy rating of -35/+45 seconds per day, and should supply years of service-free usage.


You guessed it right! Protecting the dial is Seiko’s proprietary impact-resistant Hardlex crystal. The flat Hardlex crystal comes with a very thin magnifier (cyclops) over the date display at 3 o’clock. Despite being relatively affordable, the watch glass offers impressive resistance to scratches and cracks compared to mineral crystals.

No kidding, it will survive great impact – even smashing against a rock. Moving forward, the aluminum bezel insert of the Mini Turtle is spectacular. It is fully indexed, making it suitable underwater and for timing all sorts of activities. 

The bezel is unidirectional and rotates at 120 clicks per round (anti-clockwise). It has thickset white numbering in intervals of 10 with white minute marks around, helping the wearer track time. A recessed luminous pip can be seen above the 12 o’clock position as a reversed triangle. Coloring for the bezel differs depending on the variant, but all are very well expressed and finished by Seiko.

Strap Options

The Mini Turtle is a dive watch, and depending on the model, you can choose any great strap that offers you a comfortable fit. Purists will tell you no other strap is ideal for a diver’s watch except metal, rubber, or nylon, but this is no rule.

The 42.3mm width of the case and a short lug-to-lug distance is precisely calculated to keep the Mini Turtle firmly proportioned on the wrist, so any curved end watch strap that can provide an ergonomically comfortable fit is ideal.

The use of color on the Mini Turtle is also well-balanced, which means you can choose any simple strap that is great for casual/ business casual environments depending on the model.

Bracelets, suede, perlon, NATO, and rubber straps are great options, but straps that are resistant to dust, odors, UV radiations, and sweat are highly recommended.

Top 3 Alternatives To The Seiko Mini Turtle

Seiko Prospex King Turtle SRPE03K1 

Seiko Prospex King Turtle SRPE03K1

Right up the top of the list is none other than the King Turtle SRPE03K1 with a similar bold design to the Mini Turtle. The cushion-shaped King Turtle is a particular gem in the SRP series, adored by many diving enthusiasts.

It has everything we loved in the original Turtle; 200 meters of water resistance, a screw-down crown, a day-date complication, a robust in-house movement, and a fully marked bezel. But it goes further to add almost everything the original Turtle left to be desired; a Sapphire crystal, hacking and hand-winding movement, and a bezel action that feels smoother and sturdier.

The watch is equipped with the in-house caliber 4R36 with 24 jewels and provides approximately 41 hours of power reserve. Though slightly bigger than the Mini Turtle at 45mm in diameter (hence the nickname), the King Turtle does not feel oversized on the wrist thanks to its relatively short lugs of approximately 22mm.

Expect to spend around 600 USD for a new piece, as seen on Amazon. It’s more expensive than the Mini Turtle, yes, but the Sapphire crystal upgrade is well worth the premium.

Hamilton Khaki Navy Scuba Auto H82335131

Hamilton Khaki Navy Scuba Auto H82335131

Popular for unique aviation-inspired watches, Hamilton stands out for constantly consolidating Swiss watchmaking traditions with classic American styles. Measuring 40mm in diameter, the Navy Scuba Auto from Hamilton is a perfect alternative to the Mini Turtle. From the case to the bracelet, bezel, and dial, this model is distinct and well-designed. 

Just like the Mini Turtle, it features a clean dial with large hands — the minute hands even have an arrow shape at its tips that is distinguishable thanks to its striking red color. The dial is protected by Sapphire crystal and is water resistant up to 100m. It is equipped with Hamilton’s H-10 caliber, a three-hand movement with a power reserve of up to 80 hours.

You can get it here for 650 USD or around 400 USD for the quartz variation (ref: H82201131).

Dan Henry 1970

Dan Henry 1970

Notable in the vast watch world for creating vintage-inspired timepieces is Dan Henry, a watch brand that was created by an avid watch collector. If you absolutely want to replace the Mini Turtle with a great affordable alternative, the Dan Henry 1970 is the perfect compromise because of its vintage and sporty look. 

The case measures 40mm with a lug-to-lug width of 22mm. The matte dial is all about legibility with a 60-min inner rotating bezel and a welcome addition of applied hours indices.

It is equipped with the caliber NH35 from Seiko, a reliable but affordable movement that offers a decent power reserve of approximately 41 hours. It is water resistant to a depth of 200 meters and goes for 290 USD on Dan Henry’s official website.


Once again, Seiko adheres to its proven recipe: maintaining the great points and never breaking the codes. While there are great alternatives to the Mini Turtle out there, you’ll hardly find an entry-level timepiece that offers such profound consistency in its design and quality.

The watch has been at the end of the accessible divers, and there are tangible reasons for this. The overall execution is superb, with outstanding consistency in the build and form. The accuracy of the assembly, the superiority of the parts used in all areas, robustness of the movement, comfort, and compactness of the bracelet and clasp… 

There’s no denying that everything has been considered with much attention. As for the price, the Mini Turtles have been discontinued (so hold tight to yours if you got one), making them more expensive now. Expect to spend around 370 USD for a new piece on Amazon.

About Exquisite Timepieces

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