Seiko has spent the last decade mining its own archive, and the two most beloved results are sitting on dealer shelves (or, in one case, only the secondary market) right now: the SPB143 “62MAS” and the SPB153 “Captain Willard.” Both are faithful reissues of watches that basically invented the modern Japanese dive watch — the 1965 62MAS and the 1970 ref. 6105 — and both run the same movement at a similar price. But they wear, look, and feel like two completely different watches. Here’s how to pick between them.
TL;DR
The SPB143 ($1,200 retail, Aug 2026) is the more versatile, round-cased 62MAS reissue — 40.5mm, grey sunburst dial, steel bracelet, still in Seiko’s current catalog. The SPB153 “Captain Willard” (originally $1,100, now discontinued and secondary-market-only at roughly $900–$1,200) is the cushion-cased, greener, more characterful 6105 reissue — 42.7mm, greener dial, comes on rubber. Both use the Caliber 6R35 (70h reserve, 200m WR). If you want one do-everything diver that disappears under a cuff, buy the SPB143. If you want the watch Martin Sheen wore in Apocalypse Now and don’t mind hunting the secondary market, buy the SPB153.
Table of Contents
- The History: Two Different Seiko Divers From the Same Decade
- Full Specs Comparison
- Design and Case Shape
- Movement: Both Run the Same Caliber
- On the Wrist: Sizing and Wearability
- Pricing and Availability (Aug 2026)
- How They Compare to the Rest of the Field
- Verdict: Which Should You Buy?
- FAQ
The History: Two Different Seiko Divers From the Same Decade
The 62MAS (ref. 6217-8000/8001) was Seiko’s very first purpose-built dive watch, launched in 1965. It set the template every Seiko diver since has followed: round case, unidirectional bezel, and a dial legible enough to actually use underwater. The SPB143 is Seiko’s most faithful modern remake of it, released as part of the 55th-anniversary “Save the Ocean” lineage in 2020 alongside the SPB147 (bronze-toned dial) and SPB149 (blue, limited to 5,500 pieces).
The ref. 6105 came five years later, in 1970, with a distinctive asymmetric cushion case designed to shield the crown from knocks. It earned the nickname “Captain Willard” after Martin Sheen’s character wore one throughout Apocalypse Now — a nickname that stuck so hard Seiko now uses it officially. The SPB153 is the modern reissue of the 6105, released in the same 2020 wave alongside the steel-bracelet SPB151.
Both watches share a release year, a movement, and a “Save the Ocean” heritage story — but they’re reissues of two visually opposite watches, which is exactly what makes this comparison useful. For more on where these two fit into Seiko’s full current lineup, see our Seiko Prospex Complete Guide.
Full Specs Comparison
| Spec | SPB143 “62MAS” | SPB153 “Captain Willard” |
|---|---|---|
| Case shape | Round | Asymmetric cushion |
| Case diameter | 40.5mm | 42.7mm |
| Lug-to-lug | 47.6mm | 46.6mm |
| Thickness | 13.2mm | 13.9mm |
| Lug width | 20mm | 19mm |
| Dial color | Sunburst grey | Green |
| Bezel | 120-click black steel, unidirectional | Unidirectional, green insert |
| Movement | Caliber 6R35 (automatic) | Caliber 6R35 (automatic) |
| Power reserve | 70 hours | 70 hours |
| Beat rate | 21,600 vph | 21,600 vph |
| Hacking / hand-winding | Yes / Yes | Yes / Yes |
| Water resistance | 200m / 20 bar | 200m / 20 bar |
| Crystal | Sapphire, AR-coated inner | Sapphire |
| Bracelet/strap | Steel bracelet, fold-over clasp | Silicone/rubber strap |
| Case finish | Steel with Diashield coating | Stainless steel |
| Availability (Aug 2026) | Current catalog | Discontinued, secondary market only |
| Retail price (Aug 2026) | $1,200 | Originally $1,100 (2020 MSRP) |
Design and Case Shape
This is really where the decision gets made. The SPB143’s round case and neutral grey dial make it the more office-friendly, goes-with-everything watch — it’s the diver you can wear to a meeting and to a beach without anyone blinking. The 62MAS shape is also just objectively easier to fit under a shirt cuff thanks to its shorter 47.6mm lug-to-lug and thinner 13.2mm case.
The SPB153’s cushion case is the more distinctive, more “watch nerd” choice. The asymmetric shoulder that protects the crown is a genuine design quirk you don’t see on most modern divers outside of Doxa’s SUB line, and the green dial (a deliberate callback to the original 6105’s fading-to-green lume plots) gives it a warmer, more vintage character than the SPB143’s cooler grey. It wears bigger on paper (42.7mm vs 40.5mm) but the shorter lug-to-lug (46.6mm) means it doesn’t necessarily wear larger on the wrist — it just wears differently.
If you already own a round diver — a Seiko Turtle or Samurai, for instance — the SPB153’s cushion case is the more interesting addition to a collection. If this is your first serious dive watch, the SPB143’s round case is the safer, more versatile buy.
Movement: Both Run the Same Caliber
There’s no movement decision to make here — both watches share the Caliber 6R35, Seiko’s workhorse mid-tier automatic. It offers a genuinely useful 70-hour power reserve (long enough to sit in a watch box over a weekend and still be running Monday), hacking seconds, and manual winding, none of which were guaranteed on Seiko movements a decade ago. Accuracy spec is +25/-15 seconds per day, though most 6R35s we’ve tracked in the wild run closer to +5 to +10 sec/day once regulated.
Neither watch has an exhibition caseback — both use a solid steel caseback with the “Save the Ocean” wave engraving, so the movement isn’t something you’ll be looking at day to day anyway.
On the Wrist: Sizing and Wearability
For wrists under 6.5 inches, the SPB143 is the more comfortable everyday option — the 40.5mm round case and 20mm steel bracelet sit close and taper nicely. The SPB153’s rubber strap is genuinely excellent (soft, tapered, quick-adjust) but at 42.7mm with a cushion case, it reads larger visually even though the lug-to-lug is nearly identical.
Both are 200m-rated tool watches you can actually swim and dive with, not just “water resistant” dress pieces — screw-down crowns, ISO-adjacent build quality, and factory-lumed bezels on both. Neither is a beach-only watch; both go from wetsuit to blazer cuff without feeling out of place, though the SPB143 does it slightly more convincingly thanks to the bracelet option.
Pricing and Availability (Aug 2026)
| Watch | Original MSRP | Current AD Price | Secondary Market |
|---|---|---|---|
| SPB143 | $1,200 (2020) | $1,200 (still in catalog, Aug 2026) | ~$900–$1,050 |
| SPB153 | $1,100 (2020) | Discontinued — not sold new | ~$900–$1,200 depending on condition/box-papers |
This is the practical wrinkle in the comparison: the SPB143 is still an easy purchase from any Seiko authorized dealer. The SPB153 has been quietly discontinued from Seiko’s regular lineup and now only turns up used, via gray-market sellers, or occasionally as new-old-stock — meaning you’re paying secondary-market prices (and doing secondary-market due diligence on box/papers/service history) for a “new” purchase experience you won’t get with the SPB143.
If budget and simplicity matter more than the cushion case, that alone tips the scale toward the SPB143.
How They Compare to the Rest of the Field
| Watch | Price (Aug 2026) | Case | WR | Movement |
|---|---|---|---|---|
| Seiko SPB143 | $1,200 | 40.5mm round | 200m | 6R35 auto, 70h |
| Seiko SPB153 | ~$1,000 (used) | 42.7mm cushion | 200m | 6R35 auto, 70h |
| Longines Legend Diver | ~$2,900 | 42mm round | 300m | L888.2, 64h |
| Doxa Sub 300 Caribbean | ~$2,690 | 42.5mm cushion | 300m | Cal. 32, 55h |
| Tudor Black Bay 58 | ~$3,800 | 39mm round | 200m | MT5402, 70h COSC |
What the table makes obvious: both Seikos undercut the Swiss heritage-diver competition by $1,500–$2,600 while matching or beating their water resistance and power reserve specs. The Doxa Sub 300 is the closest stylistic cousin to the SPB153 — both are cushion-cased, vintage-reissue divers — but at nearly triple the price. If you want the SPB143/SPB153 experience with a Swiss movement and don’t mind spending Tudor money, the Black Bay 58 is the obvious step up; see our full comparison in Seiko Prospex vs Tudor Black Bay.
Verdict: Which Should You Buy?
Buy the SPB143 if you want one versatile diver that works in every setting, prefer a bracelet, want the reassurance of buying new from an authorized dealer, or this is your first serious mechanical dive watch.
Buy the SPB153 if the cushion case and Apocalypse Now story genuinely appeal to you, you already own a round diver and want something different, and you’re comfortable buying carefully on the secondary market.
Either way, you’re getting the same reliable 6R35 movement and 200m of real water resistance underneath — the decision here is entirely about case shape, dial color, and how much you value buying new versus hunting for a discontinued reference.
Where to Buy
The SPB143 is readily available new through Seiko authorized dealers. For the SPB153, check secondary-market listings carefully for box/papers. A few accessories worth having alongside either watch:
- Automatic watch winder — keeps the 6R35 wound and ready if you rotate watches.
- Microfiber cleaning cloth — for the sapphire crystal and steel case.
- Bracelet link removal tool — for sizing the SPB143’s steel bracelet at home.
FAQ
Is the SPB153 still available new from Seiko?
No. As of August 2026 the SPB153 “Captain Willard” has been discontinued from Seiko’s regular catalog. It can still be found on the secondary market — via resellers, gray-market dealers, or occasionally new-old-stock — typically priced between $900 and $1,200 depending on condition and whether box and papers are included.
What’s the difference between the SPB143 and SPB149?
Both are 62MAS reissues sharing the same 40.5mm round case and 6R35 movement. The SPB143 has a grey sunburst dial and steel bracelet and remains in Seiko’s current lineup. The SPB149 has a blue dial, was limited to 5,500 pieces, and is also now discontinued from regular production.
Why is the SPB153 called the “Captain Willard”?
The nickname comes from Martin Sheen, who played Captain Willard in the 1979 film Apocalypse Now and wore an original Seiko 6105-8110 throughout the movie. The nickname stuck so firmly with collectors that Seiko now uses “Captain Willard” in its own official marketing for the modern SPB153 reissue.
Can I swap the strap on either watch?
Yes. The SPB143 uses a 20mm lug width and the SPB153 uses 19mm — both standard sizes with wide third-party strap availability. The SPB143’s steel bracelet can also be swapped for NATO, rubber, or leather straps if you want to change up the look.
Are these watches actually dive-rated, or just water resistant?
Both are genuinely dive-capable: 200m water resistance, screw-down crowns, unidirectional bezels with clear lume markers, and sapphire crystals. Neither carries the formal ISO 6425 diver’s certification that Seiko applies to some Prospex models, but both meet the practical spec for recreational scuba diving.
How does the 6R35 compare to Seiko’s older 6R15 movement?
The 6R35 replaced the 6R15 in most current Prospex models and improved the power reserve from 50 hours to 70 hours while keeping the same 21,600vph beat rate, hacking, and hand-winding functions. Both movements are based on the same architecture, but the 6R35 is the version used in the SPB143 and SPB153.
Which one is the better first mechanical dive watch?
The SPB143 is the safer first choice — its round case, steel bracelet, and grey dial are easier to wear daily across different outfits, and buying new from an authorized dealer means a straightforward warranty. The SPB153’s cushion case is a more acquired taste better suited to someone who already knows they like the vintage 6105 silhouette.
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This article was researched with the help of AI. While we strive to keep all information accurate and up to date, there may be errors. If you notice any discrepancies, please contact us.
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