Seiko Prospex Land 'Tortoise' Field Watch Ref. SRPG13 (also known as SRPG13K1)
Field Watch / Land-based Adventure Watch · Seiko (Seiko Watch Corporation). Positioned in the 'Prospex' (Professional Specifications) line, representing Seiko's mid-tier tool watch category.
Period: Modern Tool Watch (2021-present). It combines the classic cushioned 'Turtle' dive case geometry with land-specific navigation features.
Type
Field Watch / Land-based Adventure Watch
Brand
Seiko (Seiko Watch Corporation). Positioned in the 'Prospex' (Professional Specifications) line, representing Seiko's mid-tier tool watch category.
Movement
Automatic, Calibre 4R35. Features 23 jewels, 21,600 vph (3Hz) frequency, approximately 41 hours of power reserve, hacking seconds, and manual winding capability.
Dimensions
Case diameter: 42.4mm, Thickness: 11.7mm, Lug-to-lug: 45.2mm, Lug width: 20mm. It wears smaller than its diameter suggests due to the short lug-to-lug distance.
Description
The Seiko 'Tortoise' is a clever reimagining of the iconic 'Turtle' dive watch silhouette, optimized for land exploration. By slimming down the case and replacing the dive bezel with a compass scale, Seiko created a rugged, everyday field watch with a slim profile that fits comfortably under a cuff while maintaining a bold, adventure-ready aesthetic.
Key Features
Cushion 'Tortoise' case, compass bezel insert, 4:30 date position, sapphire crystal, and ground-to-air emergency codes on the caseback.
Dial Description
Textured sand-colored/beige dial with a matte, grainy finish. Features applied rectangular indices with LumiBrite, a date window at 4:30, and a distinctive orange-tipped arrow seconds hand.
Case Material
Stainless steel with a brushed and polished finish; features a unique cushion-shaped silhouette known to collectors as the 'Tortoise'.
Crystal Type
Flat Sapphire crystal. Highly scratch-resistant, providing a significant upgrade over the standard Hardlex found on entry-level Seiko divers.
Bezel Details
Bidirectional rotating compass bezel. Black aluminum insert with cardinal (N, E, S, W) and ordinal markings for navigation. Bezel is knurled for grip.
Crown & Pushers
Screw-down crown located at the 4 o'clock position. Features a textured grip and is protected by the ergonomic curve of the cushion case.
Bracelet or Strap
Green/Grey canvas (textile) strap with a leather backing for comfort, featuring a stainless steel pin buckle and specialized stitching near the lugs.
Caseback Details
Solid screw-down stainless steel caseback featuring engraved 'Emergency Signal' codes (Ground-to-Air distress signals) instead of the standard Tsunami logo.
Movement Type
Automatic, Calibre 4R35. Features 23 jewels, 21,600 vph (3Hz) frequency, approximately 41 hours of power reserve, hacking seconds, and manual winding capability.
Water Resistance
200 Meters (660 Feet). Despite being a 'Land' watch, it maintains full diver-level water resistance, making it suitable for swimming and recreational water sports.
Origin & Provenance
Japanese design and movement. Movement is the workhorse 4R35, often assembled in Seiko's Japanese or overseas facilities (K vs J designations).
Age Estimate
Circa 2021-2023. This specific colorway was part of the initial launch of the Land Tortoise series in mid-2021.
Cultural Significance
Represents the modern trend of 'crossover' tool watches—taking professional-grade heritage designs and adapting them for casual outdoor enthusiasts and hikers rather than just scuba divers.
Condition Notes
Appears to be in Excellent to Near-Mint condition. The fabric strap shows no significant fraying, and the bead-blasted/brushed finishing on the case remains crisp without visible scratches.
Value Estimate
$350 - $450 USD. Value is stable as a popular entry-to-mid-level collector piece; presence of original box and papers maintains the higher end of the range.
Care & Maintenance
Recommended service interval of 3-5 years. Ensure crown is fully screwed down before water exposure. Rinse with fresh water if exposed to salt or dirt.
Similar Watches
Seiko Prospex 'Turtle' SRPE93 (diver variant), Hamilton Khaki Field Mechanical (competitor field watch), Seiko Alpinist SPB121 (higher-end compass watch).
Interesting Facts
The 'Tortoise' name was given by the enthusiast community because while it looks like a 'Turtle' (diver), it belongs on land. It is one of the few Seiko Prospex models to feature a compass bezel instead of a dive or GMT scale.