Seiko’s Prospex SLA049 and SLA051 are 2021 reinterpretations of its 1970 diver, distinguished mainly by color and edition status. The blue SLA049 commemorates adventurer Naomi Uemura and was limited to 1,200 pieces; the charcoal-gray SLA051 joined the regular Prospex collection. Both share an automatic Caliber 8L35, a 200-meter diver’s rating and the original model’s asymmetrical case shape.
How the SLA049 and SLA051 differ
Seiko announced both watches on February 24, 2021, with availability scheduled for July 2021. The company described them as sharing the same case design, features and specifications. Their principal differences are the dial and bezel color, commemorative details and edition status.
| Feature | Prospex SLA049 | Prospex SLA051 |
|---|---|---|
| Edition | Naomi Uemura 80th Anniversary Limited Edition; limited to 1,200 pieces | Charcoal-gray model in the Prospex collection |
| Dial and bezel | Blue patterned surfaces inspired by mountain landscapes and upper-atmosphere blues | Charcoal-gray patterned dial, closer in color to the 1970 original |
| Case-back marking | Engraved with Uemura’s name and an individual serial number | Not stated in Seiko’s announcement |
| Additional strap | Silicone strap included in addition to the steel bracelet | Not stated in Seiko’s announcement |
| Approximate US recommended price at launch | $3,100, stated by Seiko in 2021 | $2,900, stated by Seiko in 2021 |
The prices are launch-era US recommended retail prices, not current market quotes. Seiko’s announcement does not establish present stock, retailer pricing or resale values.
Shared case, movement and specifications
Both references retain the 1970 diver’s asymmetrical case extension, which protects the crown at four o’clock. The case measures 44 mm in diameter and 13 mm thick. Seiko specifies 200-meter diver’s water resistance for the modern models; the 1970 original was rated to 150 meters.
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- Movement: Seiko automatic Caliber 8L35, with 26 jewels, a 50-hour power reserve and a frequency of 28,800 vibrations per hour (8 beats per second).
- Case and bracelet: Super-hard-coated stainless steel, with a five-row steel bracelet.
- Crystal: Dual-curved sapphire with anti-reflective coating.
- Water resistance and sealing: 200-meter diver’s water resistance, screw-down crown and screw case back.
- Magnetic resistance: 4,800 A/m.
- Clasp: Three-fold clasp with push-button release, secure lock and extender.
Why Naomi Uemura is part of the watch’s story
The 2021 models reinterpret Seiko’s 1970 diver, which had luminous hands and indexes, a protected crown and 150-meter water resistance. Seiko says Uemura wore that watch on his solo dog-sled journey from Greenland to Alaska in 1974–1976, a journey the company’s US announcement gives as 12,500 km.
Uemura was born in 1941. Seiko’s account says he became the first Japanese mountaineer to summit Everest in 1970, then reached Denali three months later, becoming the first adventurer to summit the highest peaks on all five continents. His listed climbs were Mont Blanc in July 1966 (4,807 m), Kilimanjaro in October 1966 (5,895 m), Aconcagua in February 1968 (6,960 m), Everest in May 1970 (8,848 m) and Denali in August 1970 (6,194 m).
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In 1984, Uemura successfully climbed Denali in winter and disappeared on the descent. Seiko says he received Japan’s National Honor award after his disappearance. The SLA049’s engraved case back and limited-edition status connect the anniversary model specifically to his legacy.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.What Seiko’s launch announcement establishes
Seiko announced the watches on February 24, 2021 and scheduled them for July 2021 availability. Its published figures establish the original recommended US prices, but do not indicate what either reference costs today or whether it is currently available. For a present-day purchase, check the exact reference, seller, condition and asking price rather than relying on the 2021 launch figures. Read Seiko’s February 24, 2021 US announcement.
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- AUTOMATIC & MANUAL: SRPE05 automatic watches for men power up with your natural movements, and feature the ability to wind manually, with 41 hours of reserve power
- WATER-RESISTANT: these rugged stainless steel dive watches for men feature a khaki green silicon strap, and are both stylish and robust, following ISO standards for scuba, and are water-resistant to 200 meters
- 4R36 CALIBER: equipped with the reliable 4R36 caliber, these precise men’s wrist watches ensure the most accurate timekeeping
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- Featuring our Eco-Drive technology – powered by light, any light. 200 Meters Water Resistant and 5 Year Limited Warranty
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