Seiko Introduces Three New Prospex King Sumo PADI Diver Automatic Watches

Premium specs and tweaked aesthetics add “King” to the supersized Prospex Sumo collection.


Seiko is no stranger to dive watches, offering some of the most capable of any brand at attainable prices. It started in 1965 with the 62MAS diver and there’s a seemingly endless variety today, from Seiko 5 to pricey high-beat offerings. Prospex divers have a history of interesting nicknames like Samurai, Turtle and Monster, and the Sumo line should never be overlooked. With oversized cases and pro specs, a modernized Prospex Sumo collection of three just launched with a more prestigious title, King Sumo. Tragically, they otherwise go by Seiko’s infamous reference numbers – SPB321J1, SPB323J1 and SPB325J1.

The case size is a bit polarizing at 45mm in diameter, but for serious divers, maximum visibility is important. Thickness isn’t too bad at 12.9mm and the case has a specialized (Super-Hard) coating to increase hardness by up to three times. An additional upgrade for durability is ceramic for the bezel insert, which also resists color fading. It comes in either black or dark blue (matching the dial) and features a detailed 60-minute scale with a luminescent dot at the 12 o’clock marker. The screw-down crown is positioned at 4 o’clock, a common design for Seiko, and water resistance is rated at 200 meters. A sapphire crystal protects the dial and the screw-down case back is solid. 

The three models include a gradient blue dial (SPB321J1), gradient grey dial (SPB323J1) and PADI – Professional Association of Diving Instructors – with a black dial (SPB325J1). The gradient dials have a subtle wave pattern, while the PADI dial has an abstract global pattern showing latitude and longitude. Unlike the Prospex King Turtle or Samurai models, which have the same general aesthetic, there isn’t a cyclops lens over the date at 3 o’clock. There are classic silver Seiko applied indices (with “Sumo Belt” index at 12 o’clock) and hands with Seiko’s Lumibrite, although the PADI model has a blue minute hand and blue marks for the first 20 minutes on the bezel. The PADI hour and seconds hands are also black. A new three-link stainless steel bracelet comes with the gradient models (better fit to the lugs and case), while the PADI model has an accordion-style silicone strap (first seen with 1975 models). The bracelets have a folding clasp with secure lock and wetsuit extension. 

Powering the trio is Seiko’s in-house caliber 6R35 automatic. It’s an upgrade to prior models and features 24 jewels, a beat rate of 3Hz and a sizeable 70-hour power reserve. Functions are simple with central hours, minutes, hacking seconds and date, and it offers a level of magnetic resistance, 4,800 A/m (60 gauss). Accuracy is rated at -15/+25 seconds per day, but those are maximum figures and it’s generally better in practice. 

The two gradient models (SPB321J1 and SPB323J1) retail for EUR 1,250/GBP 940, while the PADI model (SPB325J1) retails for EUR 1,100/GBP 940. A bit pricey for Seiko divers, but with the upgraded specs both inside and out, it’s not bad for such focused, professional dive watches. 

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