The green Seiko Prospex SPB153 is the model often nicknamed the “Willard”; Seiko’s official reference is SPB153, not SBP153. It is a 1970 Heritage Diver’s Watch with a manufacturer-rated 200 m water resistance, a 42.7 mm case and Seiko’s automatic 6R35 movement. Those published specifications make it a substantial, feature-rich dive-style watch on paper, but they do not establish how a particular example wears or performs in independent testing.
What the Seiko SPB153 is—and why it is called the Willard
Seiko identifies the SPB153 as a Prospex Sea 1970 Heritage Diver’s Watch. “Willard” and “Captain Willard” are enthusiast and watch-media nicknames, not the official product name. Hodinkee’s 2020 launch report describes the SPB153 and its sibling, the SPB151, as modern reinterpretations of Seiko’s 6105 “Second Diver,” and connects the nickname to the watch’s association with the film Apocalypse Now. Hodinkee’s launch report provides that historical context.
The article’s title spells the reference SBP153, but the manufacturer’s product page and watch coverage identify this green model as SPB153. Use SPB153 when searching or checking a listing; do not confuse it with Seiko’s unrelated SBPX153 solar model.
SPB151 vs. SPB153: what changes?
Hodinkee’s launch coverage distinguishes the two related models by color and supplied bracelet or band configuration. The specifications below describe the launch variants, not current regional availability.
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- STUNNING BLUE DIAL: this rugged sports watch features a beautiful Manta Ray-patterned blue dial, with Lumibrite dial indicator hands and markers for low light and a magnified day/date calendar
- BLACK BEZEL: this versatile men’s watch features a black ceramic unidirectional bezel with distinctive scalloped edging, for elapsed timing
- AUTOMATIC & MANUAL: SRPF77 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 deep blue silicone 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
| Model | Dial and bezel | Supplied configuration |
|---|---|---|
| SPB151 | Black dial and black bezel | Bracelet |
| SPB153 | Olive-drab green dial and bezel | Silicone band |
Hodinkee reported 2020 launch prices of $1,300 for the SPB151 and $1,100 for the SPB153, with expected availability in June 2020. Those are historical launch details, not current prices or evidence of present stock. See the 2020 launch report.
Seiko SPB153 specifications
These are the manufacturer-published specifications on Seiko’s UK SPB153J1 product page, accessed in 2026. The stated accuracy range is a specification, not an independent measurement of a review sample.
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- WATER-RESISTANT: these water-resistant men's dive watches are ISO scuba-approved to depths of 200 meters
- AUTOMATIC: these self-winding, automatic men's watches are powered by your movement, with a power reserve of 41 hours
- STAINLESS STEEL: features a durable 43.8mm stainless steel watch case and bracelet.
- LUMIBRITE DISPLAY: this men's automatic watch features a highly-legible display with LumiBrite hands and markers
- 4R35 CALIBER: equipped with the reliable caliber 4R35 automatic movement, this accurate men's watch keeps precise time
| Specification | Seiko-published detail |
|---|---|
| Reference and collection | SPB153J1; Prospex Sea 1970 Heritage Diver’s Watch |
| Case | Stainless steel; 42.7 mm diameter, 13.2 mm thick, 46.6 mm lug-to-lug |
| Crystal | Curved sapphire crystal; anti-reflective coating on the inner surface |
| Movement | Caliber 6R35 automatic with manual winding; 24 jewels; stop-seconds; date display |
| Stated precision | +25 to −15 seconds per day |
| Power reserve | Approximately 70 hours |
| Water resistance and controls | 200 m / 660 ft diver’s water resistance; unidirectional rotating bezel; screw-down crown; screw case back |
| Dial and bezel illumination | LumiBrite on hands, indices and bezel |
| Band and clasp | Silicone band; three-fold clasp with secure lock |
| Lug spacing | 20 mm |
| UK listing price | GBP 1,050 displayed on Seiko’s UK page at access time; regional listing, not a universal price or a guarantee of stock |
Check Seiko’s UK SPB153J1 product page for its current regional listing and specifications.
Is the SPB153 a real dive watch?
Seiko rates it for 200 m / 660 ft diver’s water resistance and specifies a unidirectional rotating bezel and screw-down crown. Those are meaningful dive-watch features in the published specification. The rating describes the watch as specified by the manufacturer; it does not prove that an individual used watch remains water-resistant. For an older or pre-owned example, condition and a recent pressure test matter more than the original rating.
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- Iconic Promaster watches with advanced functions designed to venture to the deepest depths.
- 3 Hand, Date
- Silver-Tone Stainless Steel
- Luminous Hands and Markers and Anti-Reflective Mineral Crystal
- Featuring our Eco-Drive technology – powered by light, any light. 200 Meters Water Resistant and 5 Year Limited Warranty
How large is the SPB153?
Seiko lists a 42.7 mm case diameter, 13.2 mm thickness and 46.6 mm lug-to-lug length. The lug-to-lug measurement helps describe the span across the wrist, while the case diameter alone does not determine fit. These dimensions are manufacturer figures; no wrist-size or hands-on comfort testing is established here.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Movement and power reserve
The SPB153 uses Seiko’s 6R35 automatic movement, which can also be wound manually. Seiko lists approximately 70 hours of power reserve, a date display, stop-seconds and a stated precision of +25 to −15 seconds per day. Treat the accuracy range as the manufacturer’s published specification, not a promise that every watch will keep time within that range in every position or condition.
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- KHAKI GREEN DIAL: this rugged sports watch features a khaki green dial patterned to mirror the shape of the bezel’s edge, with Lumibrite dial indicator hands and markers for low light and a magnified day/date calendar
- BLACK BEZEL: this versatile men’s watch features a black ceramic unidirectional bezel with distinctive scalloped edging, for elapsed timing
- 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
What strap fits the SPB153?
Seiko specifies a 20 mm distance between the lugs and supplies the SPB153 with a silicone band. A 20 mm strap is therefore the sensible starting size when shopping for an alternative. The lug width alone does not confirm that every third-party strap will fit correctly: check the end shape and clearance, spring-bar compatibility, clasp, strap length and preferred material before buying.
Should you buy the SPB153?
The SPB153 is a strong candidate if you want Seiko’s green 1970 Heritage diver design, a manufacturer-rated 200 m water resistance, sapphire crystal, a 20 mm strap setup and an automatic movement with a published reserve of about 70 hours. The main practical questions are whether its 42.7 mm case and 46.6 mm lug-to-lug dimensions suit you, whether you prefer its silicone band to the SPB151’s bracelet, and whether the price and warranty in your region make sense. Seiko’s UK page displayed GBP 1,050 when accessed in 2026; that should not be treated as a global quote or confirmation of local availability.
For a secondhand watch, ask for its service history, verify the seller and applicable local warranty, and have water resistance tested before relying on it in water. The Philippines Seiko Boutique page states a three-year guarantee for purchases through that store only; it is not a universal warranty promise. Seiko Boutique Philippines’ SPB153J1 listing gives that store-specific condition.
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Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
