2017 Seiko Prospex "Blue Lagoon" Turtle Limited 44.5mm SRPB11K1

Here we have a 2017 Seiko Prospex "Blue Lagoon" Turtle Limited 44.5mm SRPB11K1, a vibrant and highly sought-after professional dive watch. Released as a strictly limited edition to celebrate Seiko’s rich diving heritage, this rare collectable features a captivating aquatic colourway inspired by the deep, crystalline waters of a tropical lagoon. The commanding 44.5mm stainless steel case uses Seiko’s iconic cushion-shaped "Turtle" silhouette, curving beautifully over the wrist for an incredibly comfortable, ergonomic fit. A remarkably compact lug-to-lug length of 47mm and a sleek case thickness of 12.5mm give this watch a balanced yet powerful presence on the wrist. Polished and brushed surfaces transition into razor-sharp lines, flanking the signature recessed screw-down crown at 4 o’clock, which safely secures a robust, ISO-certified 200-metre (20 ATM) water resistance rating. A 120-click unidirectional rotating bezel frames the face, fitted with a distinctive dual-toned blue-and-turquoise aluminium insert for tracking elapsed dive time. A durable, impact-resistant Hardlex crystal sits above a stunning sunburst blue dial that delivers a vibrant, high-contrast aesthetic when it catches the light. The dial features Seiko's classic oversized Lumibrite hour markers and broad hands, heavily infilled to ensure exceptional legibility in dark depths, complemented by a pop of bright yellow on the sweep seconds hand and minute track markers. Positioned cleanly at 3 o’clock, a day-date window adds effortless daily utility. Inside beats the rock-solid automatic Seiko Cal. 4R36 movement, a legendary mechanical workhorse operating at 21,600 vibrations per hour (3Hz). Featuring hacking seconds and hand-winding capabilities, this 24-jewel calibre relies on Seiko’s Diashock system for superior shock resistance. This exclusive reference comes paired with its original 20mm integrated three-link stainless steel bracelet, featuring satin-finished surfaces, polished accents, and a secure folding clasp with a wetsuit extension lock; all links are provided, plus a 20mm rubber strap and 20mm NATO strap. This watch is sold with its original Seiko box and paperwork.

This watch is sold with its original Seiko box and paperwork. The watch comes paired with its original 20mm three-link stainless steel bracelet, featuring satin-finished surfaces, polished accents, and a secure folding clasp with a wetsuit extension lock; all links are provided, plus a 20mm rubber strap and a 20mm NATO strap. The watch is from July 2017 and is in worn condition, but overall it is in fair condition, as you can see from the photographs. The watch comes with our 12-Months Warranty.

The Seiko Turtle is possibly one of the best-wearing bigger watches out there, especially when it comes to proper dive watches. At 44.5mm, it sounds substantial on paper, but the wonderfully curved cushion case and short 47mm lug-to-lug make it hug the wrist incredibly well. It’s a design that really proves you can’t judge a watch by diameter alone. Add in the fantastic Blue Lagoon colourway, and you’ve got a big, bold Seiko diver that’s remarkably comfortable and a lot of fun on the wrist. I would not hesitate to add this limited edition to your collection today!

Reference : SRPB11K1 (4R36-06A0)
Movement : Automatic Seiko Cal. 4R36
Age : July 2017
Year : 2017
Case Size : 44.5mm
Case Thickness : 12.5mm
Lug to Lug : 47mm
Lugs : 20mm
Condition : Pre-Owned
Box and Papers : Box & Papers
Case Material : Stainless Steel
Warranty : 12-Months Warranty
The wrist model's wrist size is 7inch

Seikos history began in 1881 when Kintaro Hattori established the K. Hattori retail and repair store. In 1892, Seikosha was established to make wall clocks. 1895 saw the production of their first pocket watch. 1913 saw the launch of their first wristwatch, the Laurel. In 1924, the first Seiko was manufactured. Daini Seikosha (now Seiko Instruments Inc.) was established in 1937. Seiko was listed on the Tokyo Stock Exchange in 1949. The Suwa factory became independent and formed Suwa Seikosha Co., Ltd. (now Seiko Epson Corporation in 1959). In 1956, Seiko launched Marvel as their first true in-house-made watch; they continued to make this watch until 1959. The Seiko Lord Marvel, introduced in 1958, was Seiko's first luxury watch, predating the well-known Grand Seiko. It was designed to rival Swiss brands with a refined design and higher specifications. In 1967, Seiko launched the calibre 5740C watch movement, a significant upgrade over the earlier calibre 5740A, which beat at 18,000, and the 5740B, which beat at 19800. This movement was special because it allowed the watch to run at a high speed of 36,000 beats per hour, making it Japan's first high-frequency watch. In fact, it was only the second watch movement of its kind in the world, following one released by a Swiss brand just a few months earlier. Japan’s first chronograph watch was introduced for the 1964 Tokyo Olympics; it was called the Seiko Crown Chronograph monopusher. Not stopping there, Seiko launched Japan's first true divers' watch, the Seiko Diver’s 150M, fitted with the automatic Calibre 6217, which was later given the nickname “62MAS” by collectors. King Seiko and Grand Seiko emerged as prominent lines within the Seiko brand, with King Seiko making its debut in 1961 as a distinguished luxury watch collection. Grand Seiko, on the other hand, has consistently set the standard for exceptional craftsmanship and precision engineering. In 1965, Seiko introduced a groundbreaking manual-wind movement featuring 25 jewels and hacking seconds, coinciding with the launch of the second-generation KSK series, which boasted sharp, angular cases and robust, flat-ended lugs. The King Seiko KCM was introduced in 1969, featuring a chronometer-certified movement that operates at an impressive 36,000 beats per hour, along with a sleek C-shaped stainless steel case. In 1975, the King and Grand Quartz brands were introduced, built at the Suwa Seikosha and Daini Seikosha factories. In 1977, a high-end Twin Quartz Cal.92 was produced until 1979, when the 97KQ and 99KQ were introduced. The final 1981 King Quartz Cal.94KQ movement remained in production until Seiko ended the King Seiko line in 1985. Despite the challenges during the Quartz crisis of the 1970s that led to the gradual shutdown of King Seiko production, Seiko made a comeback in 2022 by reintroducing the classic King Seiko collection. The company name was changed to the Seiko Corporation in 1990. Innovation at Seiko continues today with GPS Solar watches.