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“Tuna”
Seiko Prospex Marinemaster Professional, 49.4 mm (7C46)
Collector nickname. Where the name comes from
3 versions of this watch are on Seiko's own sites right now, across 19 regions. Last checked Nov 13, 2026.
Estimated US price: About $2,445 to $3,045, converted from Seiko's list prices in AUD, CAD, CHF and more.
Retailers ask: $2,300 across 1 listing at 1 seller, checked Nov 13, 2026. See the sellers
Photos are Seiko's own, shown from Seiko's sites. Click a photo to jump to that version.
- Calibre
- 7C46
- Case diameter
- 49.4 mm
- Thickness
- 16.3 mm
- Lug to lug
- 49.4 mm
- Variants listed now
- 3
- Regions
- 19
Listed means the watch was on an official Seiko regional site or store at the last check. It does not mean it is in stock, and it does not tell us whether Seiko is still making it.
Versions listed now
Same case and movement in every row. What changes is the colour, the strap or bracelet, the finish and where Seiko sells it. Seiko's spec sheets don't state dial colour, so a colour appears only where Seiko's US store tags one.
| Photo | Reference | Colour | Strap / bracelet | Case | Edition | Listed in | Seiko list price | Buy | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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 | S23631 Also coded S23631J1 | Not published | Silicone 119 g | Not stated | Regular | 18 regions | 3,180 EUR Germany & Austria · Nov 13, 2026 about $3,045 in US dollars | No seller matched yet | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Where Seiko lists it (22 sites) and its list prices
Buying options (0)No seller offer has been matched to this exact variant yet. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
 | S23635 Also coded S23635J1 | Not published | Silicone 118.5 g | Ceramic/titanium with stainless steel bezel | 1986 Quartz Diver's 35th Anniversary Limited Edition | 2 regions Australia, Philippines | 4,100 AUD Australia · Nov 13, 2026 about $2,670 in US dollars | No seller matched yet | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Where Seiko lists it (2 sites) and its list pricesBuying options (0)No seller offer has been matched to this exact variant yet. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
 | SBBN047 “Darth Tuna” Fratello | Not published | Silicone Translated from Seiko's regional page 118.5 g | Not stated | Regular | 1 region Japan | 390,500 JPY Japan · Nov 13, 2026 about $2,445 in US dollars | From 2,300.00 USD Japan Select · 1 seller checked | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Where Seiko lists it (1 site) and its list prices
Buying options (1)Offers seen available at the last check come first, then by item price. Shipping, taxes and import charges are not included. Commission never affects the order.
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Where to buy
Asking prices for new watches at the last check. Each was in stock at that check, but stock moves, and shipping, tax and import charges are not included. Each reference links to the seller's page.
| Seller | Version | Asking price | Checked |
|---|---|---|---|
| Japan Select | SBBN047 | 2,300.00 USD | Nov 13, 2026 |
Estimated US prices use Seiko's US list price where there is one. Otherwise they are the middle of Seiko's list prices in other countries, converted at rates dated Nov 12, 2026 from ExchangeRate-API (free open endpoint). Those list prices include each country's sales tax, so a converted figure usually runs higher than a US price would. Retailer prices are asking prices on the date shown, not sold prices, and leave out shipping, tax and import charges.
The build
| Movement | Quartz | Seiko product page |
|---|---|---|
| Functions | Day/Date display | Seiko product page |
| Power reserve / battery | Approx. 5 years | Seiko product page |
| Water resistance | 1000m / 3300ft for saturation diving | Seiko product page |
| Crystal | Sapphire crystal | Seiko product page |
| Lug width | 22 mm | Seiko product page |
| Seiko case codes | 7C46-0AP0, 7C46-0AR0 | Seiko catalog data |
Why these share a page
Every version here is published by Seiko with calibre 7C46 and either the same Seiko case code or the same case size. 5 reference codes lead to this page.
What people call it
A name is shown only where a source ties it to a reference on this page. Collector nicknames are not Seiko's names unless the row says so.
| “Tuna” | Collector nickname. Source names S23631. “The S23631 and the S23629 are the newest entries in Seiko’s long line of Tuna cased watches, with a distinctive, love it or hate it shroud surrounding the bezel, creating a hockey puck-like case shape.” | Worn & Wound read 2026-11-12 |
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Related lines
- “Tuna” · Seiko Prospex Sea, 49.4 mm (7C46)
Same calibre and diameter, different published case
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