When it comes to comparable watches to the Seiko Prospex Sumo (Reference: SPB101J1), there are a few options worth considering. One such watch is the Seiko Prospex Turtle (SRP777). Like the Sumo, the Turtle is a dive watch with a similar design and build quality. It also features a reliable automatic movement and a durable stainless steel case. However, the Turtle is slightly smaller than the Sumo, making it a better option for those with smaller wrists. Looking at the case and the overall design, these updated Sumo SPB321J1 and SPB323J1 are typical no-surprise models. It’s all about improving the quality, not the style. As such, the oversized dimensions of the original Sumo are maintained. No downsizing policy here, the Sumo was and still is a large watch with a 45mm diameter, a 12.9mm height and an unmistakable lug-to-lug measurement of over 52mm. Reading this will certainly stop more than one potential customer, however, keep in mind that despite what the specification sheet indicated, the Sumo has always been more comfortable on the wrist than you’ll ever imagine. But don’t expect the comfort of one of the new compact Prospex. The Sumo SPB321J1 here worn on our editor Robin’s 19cm wrist.

Because already at first glance, you will notice that the Seiko SPB103j1 and all of the other Seiko watches are big, bulky, and have a hefty weight. This is part of the personality of the Sumo, which of course goes very well with the purpose of the watches. At its very edge, closest to the crystal, it is sloped. This means the bezel sits taller than the actual crystal, which keeps it protected and minimizes the risk of getting scratches on it. Speaking of the crystal, this watch is equipped with a sapphire crystal. This is something that the predecessor did not have. A big improvement indeed. As a dive watch should, the SPB103j1 offers great legibility. It has large hour markers and hands which provide excellent contrast against the green dial. The Sumo case is a piece of art with all its mix of brushed and polished surfaces. The detail of the rotating bezel entering the case is stunning. The only downside for me is the pins and collars system for the bracelet links. I fitted the bracelet myself for my wrist and it was quite a battle.The Seiko Prospex Sumo SPB101J1 has a power reserve of approximately 70 hours. This means that it can run for up to 70 hours after being fully wound. Overall, the dial is very well executed and manages to stay true to the Sumo design, whilst adding a very vibrant colorful touch. The lime on this watch is great and glows brightly for many hours, which we expect in a dive watch. The Seiko Prospex Sumo is powered by Seiko’s 6R35 automatic movement, which provides a power reserve of up to 70 hours. The movement is accurate and reliable, and has been tested to meet Seiko’s high standards for precision and durability. When purchasing a watch which has a metal bracelet with adjustable links, we will gladly adjust the watch bracelet to fit your wrist before sending the watch to you - free of charge! The good news is that if you want to change to a different strap or bracelet, you can easily do so thanks to the drilled lugs which makes changing the bracelet a breeze.

The dial of the Seiko SPB101J1 is slightly matte which gives it a textured and rich finish and also prevents glare and distracting reflections. The dial has not changed very much from the predecessor as the text is the same, the date window still has the white squared line around it and the Prospex logo still is present. The dial is however richly filled with luminova, or as Seiko calls it “LumiBrite”, which really does glow brightly in the dark. Seiko – the brand that has become synonymous with affordable and qualitative affordable timepieces.In fact, we would even dare to say that Seiko’s watches are some of the best value money can buy if you factor in finish, quality, and durability. In 2019, under the new references SPB101J1 and SPB103J1, the Sumo was slightly revised. The overall design was maintained, with only minor alterations. The bezel insert was redesigned with a more discreet scale, a new green dial/bezel model was launched. What really changed was the use of a sapphire crystal and the new calibre 6R35, with a beefed-up power reserve. The 2022 Seiko SumoSome other updates are here for the Seiko Sumo Prospex Diver and that includes a sapphire crystal – something that Seiko seems to be phasing in for divers above the Turtle level. Plus, and maybe this will serve as controversial, the Sumo contains a bezel with conservative font for its numbers instead of the wide, stretched numerals used in versions such as the current SBDC031. To my eyes, the indices change slightly too. They appear smaller and the 12:00 marker looks a lot classier. Regarding the hands, the minutes hand is thinner and the hour hand loses its chevron and gains a bisecting line through part of the lumed surface. The watch has applied hour markers with polished metal frames and applied Lumibrite. The minutes and hour hands are sword-shaped and are quite wide. The watch is presented with the now-iconic ”Sumo” case which is, as mentioned, large, bulky, and sturdy.

Leather strap watches tend to fit without a problem for most wearers. However, watches fitted with metal bracelets often need adjusting to get the perfect fit.

Watch sizing can only be generally carried out on watches with metal bracelets, steel, titanium, gold, etc. Lastly, the Orient Kamasu (RA-AA0004E19A) is another comparable watch to the Seiko Prospex Sumo. It features a similar design with a stainless steel case and a reliable automatic movement. However, the Kamasu has a slightly smaller case size and a more affordable price point, making it a great option for those on a budget. What is particularly interesting about this design is that its design has remained more or less unchanged since it was first presented, which goes to show it is a truly timeless design. Something watch enthusiast love, and proof that Seiko has done a great job with the design. Today, we sat down to take a look at the new Seiko Sumo Prospex Diver at Baselworld 2019: an update to a fan favorite.