Seiko Prospex Marinemaster 1968 Heritage HBF003 “Save the Ocean”: Mangrove Green, 900 Pieces
The Seiko Prospex Marinemaster 1968 Heritage HBF003 “Save the Ocean” is a limited edition of 900 pieces that puts a mangrove-green dial on the 42.6 mm 1968-style diver. It runs the Calibre 8L45 with about 72 hours of power reserve and is water resistant to 300 m. Seiko lists it at GBP 3,300 and EUR 3,800 ; a US price has not been announced. Deliveries are due to begin in November 2026.
At a glance
| Detail | Specification |
|---|---|
| Reference | HBF003J1 (HBF003) |
| Case | Stainless steel, 42.6 mm diameter, 14.1 mm thick, 49.3 mm lug to lug, 20 mm lugs |
| Dial | Mangrove green, pink-gold-coloured seconds hand, LumiBrite |
| Bezel and crystal | Unidirectional bezel with ceramic insert; dual-curved sapphire |
| Movement | Calibre 8L45, automatic with hand winding, 35 jewels, 28,800 vph, +10/-5 s per day |
| Power reserve | Approx. 72 hours |
| Water resistance | 300 m (1,000 ft), screw-down crown |
| Strap | Stainless steel bracelet, three-fold clasp with 16 mm tool-free adjustment |
| Production run | 900 pieces worldwide (300 for Japan) |
| Price | GBP 3,300; EUR 3,800; CHF 3,550; JPY 506,000; AUD 5,700; US not announced |
| Availability | Seiko Boutique exclusive; deliveries from November 2026 (one outlet says November/December) |
Design: a green dial on an unchanged case
The HBF003 changes the colour and little else. Seiko says the dial takes its greens from mangrove forests, which grow where seawater meets fresh water, and Hypebeast and Man of Many tie the theme to the mangroves of Okinawa. Gear Patrol describes a sunray finish, in contrast to the grain-textured dial of the standard model. Seiko's own wording is “vibrant green”, so the finish is reported by one outlet rather than stated on the brand page.
The details that set it apart are a pink-gold-coloured seconds hand, which Hypebeast also reads as rose-gold accents, and an engraved “Limited Edition” caseback with a serial number. Everything else follows the 1968-inspired case: a broad, streamlined silhouette, a crown at 4 o'clock, a unidirectional bezel with a ceramic insert and LumiBrite on hands, indices and bezel. The case is stainless steel, 42.6 mm across and 14.1 mm thick, with a dual-curved sapphire crystal that carries an anti-reflective coating on the inner surface.
The bracelet uses a three-fold clasp with a push-button release and a slide adjuster that moves 16 mm in 2 mm steps without tools. Seiko says the extension can be retracted even when the clasp is closed, which suits wear over a wetsuit.
Movement: the 72-hour Calibre 8L45
Inside is the Calibre 8L45, an automatic movement with manual winding. Seiko specifies 35 jewels, a beat rate of 28,800 vibrations per hour, a stop-seconds function, a date display and a power reserve of about 72 hours. Stated accuracy is +10 to -5 seconds per day, and magnetic resistance is listed at 4,800 A/m.
The 8L45 matters because it is the part that changed when the current Marinemaster generation arrived. Gear Patrol reports that the HBF001, released in March 2026, kept the 1968-inspired design and the 42.6 mm case and added the 8L45, a ceramic bezel insert, a redesigned date window at 3 o'clock and a tool-free microadjustable clasp. The HBF003 keeps all of that, so it should be read as a colourway of the current model, not a new platform.
For context, Man of Many lists the black-dial SLA079J1 with the Calibre 8L35, rated at about 50 hours and +15/-10 seconds per day, against the 8L45's 72 hours and +10/-5. Our sources do not explain how the SLA079 and the HBF001 relate, so we do not draw a line between them. Our guide to Seiko calibres covers the wider movement family.
Heritage: the 1968 diver and the Save the Ocean idea
The design looks back to Seiko's 1968 diver, which Hypebeast calls the company's landmark dive watch and the first hi-beat diver in the world. Gear Patrol dates the latest all-new Marinemaster to 2024 and calls it Seiko's best diver.
“Save the Ocean” is a theme within Seiko Prospex, where colours are drawn from marine habitats. Gear Patrol notes that a previous Save the Ocean Limited Edition was priced at $3,900 in the US, though its text does not say which model that was. In this case the habitat is the mangrove, and the dial is the only place the idea shows up; by Gear Patrol's account the rest of the watch is unchanged from the March 2026 HBF001. That continuity is the point of a colourway release, since the engineering of the current Marinemaster carries over and the limited edition adds a theme and a numbered caseback. Our Seiko history pages cover the brand, and the Turtle and Sumo guides cover the more affordable divers in the range.
Seiko Prospex Marinemaster 1968 Heritage HBF003: pricing and availability
Seiko lists the HBF003 at GBP 3,300 in the UK, EUR 3,800 in Germany, CHF 3,550 in Switzerland and JPY 506,000 including tax in Japan. Man of Many reports AUD 5,700. Hypebeast converts the British price to about $4,370, using its own rate, but that is a conversion and not a US retail price.
Seiko has not announced US pricing. Gear Patrol points out that the standard HBF001 costs $3,600 and expects the limited edition to land near that figure or the $3,900 of the earlier Save the Ocean model. That is the author's expectation, so treat any US number as unconfirmed until Seiko publishes one.
The watch is a Seiko Boutique limited edition. Seiko Japan opened pre-orders on October 8, with 300 of the 900 pieces allocated to Japan. Hypebeast says deliveries begin in November 2026, in line with the Japanese release schedule, while Man of Many expects shipping in November or December. Gear Patrol expects it to sell out quickly, which is an opinion and not a fact.
Who it is for, and how it compares
The HBF003 suits a buyer who already likes the current Marinemaster and wants a distinctive dial, since the specification matches the standard model and the price is a premium for the colour and the numbered run. The 72-hour reserve and 300 m rating make it a working diver, not only a collector's piece. The 14.1 mm thickness and 49.3 mm lug-to-lug length are worth trying on, because a 42.6 mm diver with 20 mm lugs wears differently on a small wrist than the diameter alone suggests. The price puts it in the territory where buyers also weigh Swiss alternatives, which is why we point to those below. Seiko Boutique exclusivity and a run of 900 also mean availability will be tighter than for a regular catalogue model.
Against other well-known divers, the closest comparisons in our coverage are the Tudor Black Bay 58 and the Omega Seamaster Diver 300M. Our direct comparison of the Black Bay 58 and Seamaster 300M shows where that segment sits. Seiko's other recent releases are in our news on the 145th anniversary Edo Purple editions and the Power Design Project Panda chronograph.
Background
Seiko's dive-watch lineage is the context for this release. Our Seiko history hub covers the company, the Prospex line covers its sports and diving watches, and the guides to the Turtle and Sumo show how the mid-range divers developed.Sources: Seiko Watches product pages (UK, Germany, Japan and global), Hypebeast (October 12, 2026), Gear Patrol, and Man of Many, all retrieved on October 21, 2026. Prices are indicative, vary by market and may change; the US price had not been announced at the time of writing.
Frequently Asked Questions
What is the Seiko Prospex Marinemaster 1968 Heritage HBF003?
It is a limited edition “Save the Ocean” version of the current Marinemaster diver, with a mangrove-green dial, a 42.6 mm steel case, the Calibre 8L45 and 300 m water resistance. Production is limited to 900 pieces.
How much does the Seiko Marinemaster HBF003 cost?
Seiko lists GBP 3,300, EUR 3,800, CHF 3,550 and JPY 506,000. Man of Many reports AUD 5,700. A US price has not been announced, and Gear Patrol expects it near $3,600 to $3,900.
When is the Seiko Marinemaster Save the Ocean HBF003 released?
Hypebeast says deliveries begin in November 2026, matching Seiko Japan's November release schedule. Man of Many expects shipping in November or December.
How many Seiko HBF003 watches will be made?
Seiko says 900 pieces worldwide, with 300 allocated to Japan. Each has “Limited Edition” and a serial number engraved on the caseback.
What movement does the Seiko Marinemaster HBF003 use?
It uses the Calibre 8L45, an automatic with manual winding, about 72 hours of power reserve, a 28,800 vph beat rate and stated accuracy of +10 to -5 seconds per day.
Is the HBF003 different from the standard Seiko Marinemaster?
According to Gear Patrol, it keeps everything from the standard HBF001 apart from the dial, which is green with a pink-gold-coloured seconds hand, plus the limited-edition caseback.
Where can I buy the Seiko Marinemaster HBF003?
It is a Seiko Boutique limited edition, sold through Seiko's online boutique and, in Japan, through Seiko Dream Square and Seiko Boutiques. The German page also mentions dealers via Seiko's store locator.
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