The “Turtle” case design is one of the most popular and longest-lived concepts in the history of Seiko, appearing in countless guises across the brand’s lineup for decades since the release of the original 6309 dive watch in 1976. Like so many beloved Seiko nameplates from the “Pogue,” to the “Willard,” and the “John Player Special,” the “Turtle” moniker was never an official designation from the brand, but grew up organically from the brand’s robust fan community. For over 40 years, then, Seiko has always tacitly accepted the name, but never officially allowed it to influence the long-running cushion case design. The Japanese giant finally breaks this streak in 2021 for a good (and thematic) cause: raising awareness for the Oceanic Society environmental group to help preserve the world’s seven species of sea turtles with a trio of high-spec “King Turtle” variants. These three Seiko Prospex U.S. Special Edition models — the Seiko Prospex SRPH55, the Seiko Prospex SRPH57, and the Seiko Prospex SRPH59 – go beyond simply aiding the turtles, though, and spotlight some genuinely spectacular dial finishing capabilities at a remarkably affordable price point.

The familiar 45mm stainless steel cases of the Seiko Prospex U.S. Special Edition series follow the same rounded cushion pattern as the rest of the “Turtle” line, along with everything that entails. Make no mistake, this has a real sense of presence on the wrist, but the rolling bowl-shaped polished undercut, short wide lugs, and relatively low beltline make this idiosyncratic shape a manageable and immensely comfortable wear on a wide variety of wrists. Given that these are “King Turtle” variants, the fit and finish throughout is well above the standard for this price range, with “Turtle” series finishing hallmarks like the case-top radial brushing and the knurling of the crown appearing noticeably crisper and more nuanced than the standard model. This series’ use of ceramic bezel inserts remains a high point, with a deep glossy surface in either black or navy blue. Like the rest of Seiko’s Prospex divers, the line is rated for an ISO-compliant 200 meters of water resistance, thanks in part to the recessed screw-down crown at 4 o’clock. Seiko’s only real bespoke visual cue for these cases comes via the caseback, where each of the three models sports a lightly etched depiction of a sea turtle swimming. Seiko’s choice of execution here is puzzling, as there’s no mention of the Oceanic Society connection anywhere, and the positioning gives the caseback a decidedly busy look. If the turtle figure had replaced the standard central tsunami emblem, the caseback would likely feel far more balanced overall.

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Dial finishing has been a strength for Seiko across nearly its entire product line in recent years, and for the Prospex U.S. Special Edition models, the brand flexes both its creative and manufacturing muscle. All three dials use a multi-stage finishing process ranging from the crosshatch base texture to the dégradé shading, vibrant base colors, overlaid turtle-shell pattern, and the glossy final surface, and the sheer manufacturing prowess that allows Seiko to make these complex dials at a price point well below $1,000 is impressive on its own. As for the dials themselves, each one takes the signature “King Turtle” pattern in a vividly different chromatic direction. The Prospex SRPH55 is the closest this turtle shell-inspired design gets to an actual tortoiseshell look, but this is still a separate prospect from the mottled translucent look one usually associates with products like tortoiseshell glasses. Much like the Seiko Presage “Starlight” limited editions from 2017, this dial texture has a tendency to create a shifting soft highlight on the dial depending on the angle of the light, which plays dynamically into the brown gradient running from the center to the edge. Even without adding the translucent gray shell-inspired texture on top of this pattern, it’s a complex and eye-catching dial, and thanks to this multi-layered finishing approach it avoids feeling too visually literal on the wrist.

The SRPH57 and SRPH59 instead take this dynamic turtle-shell pattern and drape it in the colors of a sea turtle’s natural habitat. The SRPH57 offers a warmer, more tropical theme with its cyan shades, calling to mind the jewel-like waters of shallow equatorial seas. The turtle-shell pattern is less pronounced here as well than its brown-dial counterpart, giving this model a cleaner look in most lights. For those looking for a more traditional oceanic blue, the SRPH59 offers a balanced approach, with the turtle-shell texture striking a middle ground in visibility between the two other models. Like the cases, the dial layouts of all three Seiko Prospex U.S. Special Edition models follow the modern “King Turtle” pattern and offer a noteworthy jump in refinement over their entry-level counterparts. The applied indices are bolder and brighter with a more pronounced polished border, Seiko’s signature sword-and-arrow handset is given a bright full polish, and although the day/date display at 3 o’clock still uses clashing white date disks the unframed window inherits a slightly more refined character thanks to its smooth, rounded corners.

As with many of its stablemates, the Seiko Prospex U.S. Special Edition series uses the brand’s venerable in-house 4R36 automatic movement. The 4R36 is a solidly built and reliable mainstay of many of Seiko’s entry-level offerings, but while so much of these watches stretch far beyond their market segment the movement is more in line with expectations. It performed admirably throughout our testing session, but its 41-hour power reserve and 21,600 bph beat rate are decidedly average in the current marketplace.

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Seiko finishes the Prospex U.S. Special Edition series with both a stainless steel oyster-style three-link bracelet and the brand’s signature silicone “accordion” strap. The bracelet is shared with the rest of the “Turtle” and “King Turtle” series, and its thick construction pair well with the bold case on the wrist. That said, the shaping and finishing of the links, along with the flip-lock clasp, give off a rounded and imprecise look on close inspection despite its robust feel. The silicone straps, on the other hand, give these already bold designs some added personality, and Seiko’s use of subtle color here — muted walnut-brown for the SRPH55, deep navy blue for the SRPH59, and a refined hunter-green for the SRPH57 — complements the dials handsomely.

Both striking in its own right and pointing towards a bold new future for Seiko dial finishing, the Seiko Prospex U.S. Special Edition series is a vibrant and stylish way for the brand to fully embrace the “Turtle” nameplate after all these years. While not limited in number, all three models in the Seiko Prospex U.S. Special Edition line are available exclusively through select authorized dealers and e-commerce platforms in the United States. All three models, including the Seiko Prospex SRPH55, Seiko Prospex SRPH57, and Seiko Prospex SRPH59, carry an MSRP of $750 each. For more details, please visit

Necessary Data
>Brand: Seiko
>Model: Prospex SRPH55, Prospex SRPH57, Prospex SRPH59
>Price: $750
>Size: 45mm-wide, 13.2mm-thick, 47.7mm lug-to-lug
>When reviewer would personally wear it: Beach days or dive trips, or when looking for a bolder accent piece alternative to the standard dive watch.
>Friend we’d recommend it to first: Seiko enthusiasts looking for a statement diver, or those passionate about ocean conservation.
>Best characteristic of watch: Incredibly well-executed dial finishing for the price point, premium materials throughout, rock-solid construction.
>Worst characteristic of watch: Bracelet finishing feels somewhat soft and unfocused, 4R36 movement’s specifications may seem unrefined to some, caseback etchings risk feeling cluttered.

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