Given that the 62MAS holds the distinction of being the very first purpose-built dive watch that both Seiko and Japan ever put forward, it only seems natural that this fan-favorite vintage design would be reimagined in a contemporary form. However, Seiko has leaned very heavily into the design of the 62MAS over the years, and we have seen numerous different executions that have occupied an incredibly wide range of prices. Back in 2020, Seiko rolled out a lineup of 62MAS modern reinterpretation watches, and for its latest release of 2024, the Japanese manufacturer has just updated the series with a new generation that offers more compact cases, increased depth ratings, and new movements with longer power reserves.

At the time of launch, the new generation of Seiko Prospex 1965 Heritage Diver’s Watch reinterpretation models includes three references, with one of them being a special edition that celebrates the 100th anniversary of Seiko watchmaking. The SPB453 features a black dial and bezel, while the SPB451 is the blue version of the model, and both of these watches will be joining the collection as standard-production offerings with matching stainless steel bracelets. Meanwhile, the SPB455 features a charcoal gray colorway with gold accents, and it comes as a package with both a bracelet and an additional NATO-style strap. The secondary strap is manufactured entirely from recycled plastic bottles using a traditional Japanese braiding technique called Seichu, which results in a unique woven appearance and a structure that is nearly four times stronger than Seiko’s standard fabric straps.

The previous generation of 62MAS modern reinterpretation watches (such as the fan-favorite SPB143 and its siblings) featured 200 meters of water resistance and movements with 70-hour power reserves. However, Seiko’s goal with this latest series of Prospex divers was to increase their depth ratings up to 300 meters and their power reserves to a full three days, while simultaneously making their cases smaller and thinner, and giving them a more compact lug-to-lug profile. Generally speaking, increasing these metrics is achieved by using larger cases and movements, which means that Seiko had to get a bit creative in order to achieve its goals for this latest generation of 62MAS-inspired Prospex models. Expanding a power reserve by two hours is a fairly manageable task, although increasing the depth rating by 50% while also making the case thinner required a bit more engineering.

At 300 meters of pressure, the standard caseback would bend, and while simply fitting the watch with a thicker caseback would easily allow it to reach the required 300 meters, it would also result in a larger overall case profile. By increasing the interior angle of the caseback, Seiko was able to increase its strength while also shaving a couple tenths of a millimeter off the total height of the watch. Although I doubt too many people found the 200-meter depth rating of the previous generation of 62MAS reinterpretation models to be inadequate, the fact that Seiko was able to increase the water resistance while also creating a more compact and refined case is something that should be commended. So, what does all of this refinement actually mean in terms of the on-paper dimensions for these new Seiko Prospex 1965 Heritage Diver’s Watch models?

Measuring 40mm in diameter by 13mm thick with an overall lug-to-lug profile of 46.4mm, the new Seiko Prospex 1965 Heritage Diver’s Watch reinterpretation models are smaller in every dimension compared to the previous generation that first debuted in 2020. That said, the actual difference is fairly minimal with the new models being 0.5mm smaller in diameter, 0.2mm thinner, and 1.2mm shorter when measured lug to lug. Just like before, the new models feature cases crafted from stainless steel, which has been given the brand’s “super hard” coating for additional scratch resistance. Similarly, all three of the new watches feature curved sapphire crystals above their dials (with anti-reflective treatment on their interior surfaces), solid screw-down casebacks, and unsigned crowns at 3 o’clock that help guarantee their 300-meter depth ratings. Additionally, while their bezel inserts are made from aluminum, the markings are laser-engraved into their surfaces for superior longevity, and each of the three models has an insert that has been finished to match the color of its dial.

One of the more notable updates to accompany this latest generation of Seiko Prospex 1965 Heritage Diver’s Watch models pertains to their dial layout, which differs slightly from what you will find on previous 62MAS-inspired watches. The very first of the reinterpretation models had date windows at 3 o’clock without any type of additional luminous marker at this location. Later, to adhere to the updated ISO standards that require each index to be luminous on dive watches, Seiko added a small marker next to the date window, and this change can also be seen on other Prospex dive watches. For these latest 2024 models, the date window has been relocated to a small circular aperture at 4:30 (with a color-matched calendar disc), while a full-size hour marker now takes its place at the 3 o’clock location. Although 4:30 date windows are often a divisive topic among enthusiasts, this update was specifically done to increase low-light legibility, and just like all of Seiko’s other Prospex divers, the hands and hour markers receive ample amounts of Lumibrite to create a highly luminous display.

To achieve their increased power reserve, the new Seiko Prospex 1965 Heritage Diver’s Watch reinterpretation models are powered by the brand’s Caliber 6R55 automatic movement, which has most recently been used inside the brand’s King Seiko models, and this represents the first time that it has appeared within the Prospex collection. Running at a frequency of 21,600vph (3 Hz) with a power reserve of 72 hours, the Seiko Cal. 6R55 doesn’t offer drastically different on-paper specs compared to the Cal. 6R35 movement that can be found inside the previous generation of 62MAS reinterpretation watches, although it does offer two additional hours of power reserve to bring it up to a full three days of autonomy. Real-world performance differences between these two similar movements will likely be negligible, although this latest generation of Seiko Prospex divers is all about incremental improvements, and this also extends to the movement that powers them.

Just like the watches themselves, the bracelets fitted to the drilled lugs of the new Seiko Prospex models have also received several subtle updates that create a more refined on-wrist experience. The size of the clasp has been reduced and the length of the individual links has also been truncated to allow the bracelet to more easily conform to the shape of the wearer’s arm. While the bracelet sounds quite promising, the fit of the end links looks a bit disjointed in the initial press images. Admittedly, the 62MAS case isn’t the easiest to fluidly incorporate into the design of an end-link, although the large step that exists between the two surfaces undeniably feels slightly mismatched. While I will reserve my final judgment of the bracelet until I get a chance to see one in the metal, I’m personally most excited by the additional strap that comes with the 100th-anniversary special edition, and I would love to see variations of this woven NATO become available on other Seiko models.

Although the new Seiko Prospex 1965 Heritage Diver’s Watch models are slightly more expensive than what the brand was charging for the previous generation of 62MAS reinterpretation watches, the price increase is fairly reasonable compared to what can be observed elsewhere within the brand’s catalog. Both the black SPB453 and blue SPB451 are priced at $1,300 USD, while the special-edition 100th anniversary model costs slightly more at $1,400 USD due to its additional strap. Given the number of different 62MAS-inspired models we have seen throughout the last handful of years, I personally wish Seiko would devote more resources to some of its other famous case profiles, although this latest generation appears to be a worthy successor to the one from 2020, and I am sure we will soon see various other colors and limited editions added to the lineup. For more information on the Seiko Prospex 1965 Heritage Diver’s Watch SPB451 and SPB453, or for the Seiko Brand 100th Anniversary Seiko Prospex 1965 Heritage Diver’s Special Edition SPB455, please visit the brand’s website.