Nickname decoder
What watch is the Seiko "Turtle"?
The Seiko "Turtle" is the nickname for the Prospex cushion-case diver line, represented in this catalogue by the SRPE05: a 45 mm stainless steel case, Seiko's in-house automatic caliber 4R36 with day and date, sapphire crystal, a unidirectional bezel and an ISO-certified 200 m (20 ATM) dive rating. It sits in the mid-hundreds band.
What the nickname refers to
The name comes from the cushion-shaped case, which is rounded at the sides like a turtle shell rather than cut straight. The catalogue describes the line as an ISO-certified diver with unmatched lume and an indestructible cushion case, and that case is why the nickname attaches to every reference in the family, not to one dial colour.
On the spec sheet the SRPE05 runs the 4R36: 24 jewels, 21,600 vibrations per hour, 41 hours of power reserve, 169 components, made in Japan. The crystal is sapphire, which is unusual for Seiko at this band and worth knowing when comparing it with the Samurai, which uses Hardlex.
Turtle or Samurai
Both are 200 m Prospex automatics in the same band. The Turtle is the larger, rounder case at 45 mm with the day-date 4R36 and a sapphire crystal; the Samurai (SRPL13) is the angular 41.7 mm case on the date-only 4R35 with Hardlex. Wrist size and the crystal are the deciding lines; the comparison linked below sets the two out from the makers' figures.
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Frequently Asked Questions
Why is it called the Seiko Turtle?
Because of the cushion-shaped case, rounded at the sides like a turtle shell. Seiko does not use the name; the catalogue reference is the Prospex SRPE05.
Is the Seiko Turtle a real dive watch?
Yes. The catalogue lists it as ISO-certified to 200 m (20 ATM) with a unidirectional bezel, which is the conventional standard for a recreational dive watch.
What movement is in the Seiko Turtle?
Seiko's in-house automatic caliber 4R36 with day and date: 24 jewels, 21,600 vph, 41 hours of power reserve.
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