All Seiko lines › Prospex › Sea
“Sumo”
Seiko Prospex Sea GMT diver's, 45 mm (5K65)
Collector nickname. Where the name comes from
2 versions of this watch are on Seiko's own sites right now, across 4 regions. Last checked Nov 13, 2026.
Estimated US price: About $815 to $875, converted from Seiko's list prices in AUD, EUR, PLN.
Retailers ask: $873 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
- 5K65
- Case diameter
- 45 mm
- Thickness
- 13.2 mm
- Lug to lug
- 51.8 mm
- Variants listed now
- 2
- Regions
- 4
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 | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
 | SFK001 Also coded SFK001J1 | Not published | Not stated Clasp: Three-fold clasp with secure lock , push button release with extender | Stainless steel | Regular | 4 regions Australia, Hungary, Ireland, Poland | 789 EUR Ireland · Nov 13, 2026 about $875 in US dollars | From 789.00 EUR Seiko Boutique Ireland · 1 seller checked | ||||||||||
Where Seiko lists it (4 sites) and its list pricesBuying 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.
| ||||||||||||||||||
 | SFK003 Also coded SFK003J1 | Not published | Not stated Clasp: Three-fold clasp with secure lock , push button release with extender 182 g | Stainless steel | Regular | 2 regions Australia, Hungary | 1,200 AUD Australia · Nov 13, 2026 about $815 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. | ||||||||||||||||||
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 |
|---|---|---|---|
| Seiko Boutique Ireland | SFK001 | 789.00 EUR about $873 | 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 | Solar | Seiko product page |
|---|---|---|
| Functions | Overcharge prevention function Quick-start function 24-hour hand (dual time display function) Calendar-linked time difference adjustment function Date display | Seiko product page |
| Water resistance | 200m / 660ft diver's | Seiko product page |
| Crystal | Sapphire crystal | Seiko product page |
| Lug width | 20 mm | Seiko product page |
| Seiko case codes | 5K65-0AA0 | Seiko catalog data |
Why these share a page
Every version here is published by Seiko with calibre 5K65 and either the same Seiko case code or the same case size. 4 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.
| “Sumo” | Collector nickname. Source names SFK001J1. “The watch shape is affectionately named Sumo by Seiko fans because of its size and shape and the 12 oclock marker its a substantially strong looking timepiece.” | Seiko Watches India official online e-store (seikowatches.co.in) read 2026-11-12 |
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