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Dive watch profile · Heritage 1965

Seiko Prospex — The Japanese tool watch.

Japanese, not Swiss. The 1965 62MAS was Japan's first 150m diver. The 6105 went to Vietnam in Apocalypse Now. The modern SPB143 is the best dive-watch value in horology.

Seiko Prospex SPB143Photo by Francis Flinch via Wikimedia Commons, CC BY-SA 3.0 (source)

What is Seiko Prospex?

Seiko Prospex is the modern designation for Seiko's dive-watch and tool-watch collection — descended from the 1965 62MAS (Reference 6217-8000), Japan's first 150m water-resistant wristwatch. The Prospex range covers everyday dive watches (SRPE93 "Turtle", $600), 1965-heritage reissues (SPB143, $1,200), Marinemaster-tier capable divers (SLA037, $4,000+), and the SLA-series limited reissues. Seiko is Japanese (founded 1881 in Tokyo), but the Prospex line is foundational to global dive-watch history. We include it in the dive-watch hub because the design and engineering deserve it, regardless of national origin.

Heritage references

  • 62MAS (Reference 6217-8000, 1965) — Japan's first dive watch. 38mm steel case, 150m water resistance, automatic Caliber 6217. Distinguished by no crown guards and a clean aluminum bezel insert. Issued to Japanese self-defense forces and used by Japanese Antarctic researchers.
  • 6105 "Captain Willard" (1968-1976) — Cushion case, 150m water resistance, automatic Caliber 6105B. Worn by Martin Sheen in Apocalypse Now. The 6105-8110 reference is the cult collector's choice.
  • 6309 "Turtle" (1976-1988) — The mass-production diver. Cushion case, 150m water resistance, automatic Caliber 6309 (the workhorse Seiko movement of the era). Inexpensive at retail when produced; widely available on the vintage market.
  • 7C46 Tuna and Marinemaster (1986-present) — Saturation-diver capable references. The original 7C46 Tuna (Reference 7549-7000, 1975) was the world's first 600m quartz dive watch.

Modern Prospex collection

  • SRPE93 "Turtle" ($600) — 45mm cushion case, 200m WR, automatic 4R36 movement. The most-recommended sub-$1,000 mechanical dive watch.
  • SPB143/SPB147 ($1,200) — 40.5mm 62MAS-inspired case, 200m WR, automatic 6R35 movement (70-hour power reserve). The modern reference Seiko diver.
  • SPB153 "Captain Willard" ($1,500) — Cushion case 6105 reissue, 200m WR, 6R35 movement.
  • SPB237 "Captain Willard" ($1,200) — Lower-cost cushion case reissue, 200m WR.
  • SLA017 / SLA037 / SLA063 ($4,000-$6,500) — Marinemaster-tier limited editions. 8L35 mil-spec movement, hand-finished, <3,000 piece runs. The serious collector Prospex.
  • Tuna SBBN045 / Tuna SLA041 ($1,500-$3,500) — Modern saturation-diver references. 1,000m water resistance, helium escape valve.

What's worth knowing

The SPB143 is the most-recommended dive watch in the $1,000-$1,500 range. The 62MAS-inspired proportions (40.5mm), 70-hour power reserve, and quality of finish exceed nearly any Swiss-made alternative at the price point. For buyers who want a serious mechanical dive watch under $1,500, the SPB143 is the canonical answer.

Seiko's vertical integration is unusual. The company produces its own movements, hairsprings, balance springs, and many components in-house — a level of vertical integration matched only by Rolex and a handful of Swiss makers. The Prospex tier sits below Grand Seiko (Seiko's haute-horlogerie line) but uses the same design and engineering culture. The SLA-series Marinemaster references are widely considered comparable to $5,000+ Swiss dive watches in finishing quality.

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Frequently Asked

On Seiko Prospex

Is Seiko a Japanese or Swiss watchmaker?

Japanese. Seiko was founded in Tokyo in 1881 by Kintaro Hattori. Manufacturing is in Japan (Iwate Prefecture, the Shizukuishi Watch Studio for Grand Seiko, the Shinshu Watch Studio for Spring Drive). Seiko is one of the only major watchmaking nations outside Switzerland with comparable horological depth — the Spring Drive movement (1999) is one of the most important horological inventions of the past 50 years, and the 6105 movement (1968) was among the first automatic dive-watch movements with 200m water resistance from a non-Swiss maker. We include Seiko in the dive-watch hub because the Prospex line is foundational to dive-watch history, even though Seiko is not Swiss.

What is the 62MAS?

The 62MAS (Reference 6217-8000) is Seiko's first dive watch — released 1965, the same year as the Apollo program's first mission. The 62MAS was Japan's first 150m water-resistant wristwatch and was issued to Japanese self-defense forces. The watch is a reference design for modern Seiko dive watches and has been reissued multiple times — most notably as the SLA017 (2017, $4,000+, limited) and SLA037 (2020, $4,000+). The original 62MAS examples in good condition trade for $5,000-$15,000 on the vintage market.

What is the "Captain Willard"?

The Captain Willard is the Seiko 6105-8110 dive watch worn by Martin Sheen as Captain Willard in Francis Ford Coppola's <em>Apocalypse Now</em> (1979). The 6105 was Seiko's second-generation dive watch — released 1968, automatic 6105B movement, 150m water resistance, cushion case. The watch became cult-collected after the film's release. Original 6105-8110 examples trade for $2,000-$5,000. Modern reissues (SPB153, SPB237) preserve the cushion-case aesthetic at $1,200-$1,500.

Which modern Seiko Prospex should I buy?

Best entry: Seiko Prospex SRPE93 ($600) — the modern "Turtle" reissue, 45mm cushion case, 200m WR, 4R36 movement. Best $1,000-tier: SPB143 ($1,200) — the modern 62MAS reissue, 40.5mm, 6R35 movement. Best capable diver: SLA037 (limited, $4,000+) — Marinemaster-tier, 8L35 movement, mil-spec dive watch. Best vintage flavor: SBDC101 ($1,500) — alpinist crossover. The Prospex range is the best dive-watch value in horology under $5,000.

What is The Essential Watch Guide?

The Essential Watch Guide is an editorial publication covering luxury watchmaking — Swiss heritage houses, dive watches, vintage timepieces, and the makers worth knowing. Coverage includes Rolex, Patek Philippe, Audemars Piguet, Vacheron Constantin, Omega, Tudor, and dozens more. Editorial focus: history, signature collections, what to look for when buying, and how value holds.

Which Swiss watch brands are the most prestigious?

The "Holy Trinity" of Swiss watchmaking is Patek Philippe (founded 1839), Audemars Piguet (1875), and Vacheron Constantin (1755) — the three houses widely considered the apex of haute horlogerie. Rolex is the most recognized worldwide; Jaeger-LeCoultre supplies movements to many top brands; Blancpain is the oldest continuously operating watchmaker (founded 1735). Independent makers like F.P. Journe and Richard Mille operate at the same tier with smaller production runs.

What makes a watch "Swiss made"?

Swiss law requires that a watch labeled "Swiss made" must have its movement assembled in Switzerland, its movement cased in Switzerland, undergone final inspection by the manufacturer in Switzerland, and have at least 60% of its production cost incurred in Switzerland. The standard is enforced by the Federal Council and the Federation of the Swiss Watch Industry FH.