Although Isotope often embraces a fun and playful design language, the brand is also entirely capable of producing watches on the more serious side of the spectrum. That said, even at their most utilitarian and conservative, Isotope’s models still retain a certain lighthearted quality to their designs, and regardless of the specific collection or colorway, they always showcase the brand’s distinct aesthetic DNA. As its latest release for 2023, Isotope has collaborated with renowned ice diver Johanna Nordblad to create the most purpose-built and function-forward version of its Hydrium dive watch that has been put forward thus far. Known as the Isotope Hydrium Pro Nordblad Limited Edition, this highly utilitarian rendition swaps out the bright and playful colors of other models from the Hydrium series, and exchanges them for an ultra-legible display and specifications that exceed the requirements for ISO 6425 certification. 

Johanna Nordblad is a world record-breaking freediver from Finland, who after suffering a severe leg injury in 2010, discovered ice diving as a way of combining one of her greatest passions with the healing properties of cold water. Swimming under the ice on a single breath of air is inherently rather dangerous but also incredibly fascinating (be sure to check out Johanna ice diving with the Hydrium Pro Nordblad in the video below), and Netflix even created a BAFTA-nominated documentary about Johanna Nordblad titled “Hold Your Breath: The Ice Dive,” which takes viewers on a journey through the day that Johanna became the world champion. 

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In addition to being designed in collaboration with Johanna Nordblad, Isotope also takes things one step further when it comes to verifying the real-world capabilities of the Hydrium Pro Nordblad Limited Edition, and the new model is the first from its Hydrium Pro series, which are professional-oriented dive watches designed to exceed the standards outlined by ISO 6425 specifications. Given that Isotope is a UK watch brand, it would actually be the BSI (British Standards Institution) who would be the organization in charge of issuing certifications for dive watches; however, with three times the necessary water resistance and a chunky case constructed from stainless steel and sapphire, the Isotope Hydrium Pro Nordblad significantly surpasses all of ISO 6425’s requirements. While the 300-meter depth rating and on-paper stats are identical to other Hydrium and HydriumX models, the more function-forward design of its display offers superior legibility, and it almost looks like a futuristic version of a Blancpain Fifty Fathoms that comes from some alternate reality or alien planet.

From an external case perspective, the new Isotope Hydrium Pro Nordblad appears to be largely identical to other Hydrium and HydriumX dive watches, which means that it features the same 40mm micro-blasted stainless steel case with a screw-down crown, 120-click unidirectional rotating bezel, domed sapphire crystal, and a screw-down caseback with a flat sapphire display window. I’m personally a big fan of this fun and chunky case that Isotope uses across its various Hydrium and HydriumX dive watch models, and if you want my full thoughts on the case and how it wears on the wrist, be sure to check out my full hands-on review of the Isotope HydriumX “The Judge,” which you can find right here

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While the actual case of the Hydrium Pro series appears to be identical to other Hydrium and HydriumX models, one key update to the external side of the watch is in regards to its bezel insert, which now offers a significantly more functional overall design. Although it is still crafted from scratch-resistant synthetic sapphire, the black-colored insert now features luminous markings every five minutes with Arabic numeral cardinal points, plus a fully demarcated luminous scale for the first fifteen minutes. While the insert still features Isotope’s signature lacrima (teardrop) emblem for its zero marker, the additional luminous markings enable the bezel on the Hydrium Pro Nordblad to be used for more precise timing capabilities, which is something that was missing from some of the brand’s previous dive watch models. 

Just like its bezel insert, the dial fitted to the Isotope Hydrium Pro Nordblad Limited Edition offers a similar function-forward design with a matte black surface and crisp white markings. The only pop of color is the bright blue “Nordblad” text below the “Hydrium Pro” signature, and this same colorful highlight is echoed on the seconds hand, which appears in Isotope’s extended lacrima shape, with a white luminous segment near its tip. Large printed baton markers with prominent Arabic numerals at the poles offer a clear orientation of the time, and unlike many other Isotope watches, the dial fitted to the Hydrium Pro Nordblad lacks the large lacrima motif that often occupies the central section of the display. Additionally, rather than having the stylized HydriumX handset that is inspired by the famous “Will Return” shop signs that hang in store windows around the world, the Isotope Hydrium Pro Nordblad features the brand’s “i” hands, as they ultimately offer superior at-a-glance legibility.

Beyond the dial, hands, and bezel insert, everything else appears to be right in line with the rest of the greater Hydrium series, including its Swiss Landeron 24 automatic movement, which is based on the core architecture of the ETA 2824 and runs at a frequency of 28,800vph (4 Hz) with a power reserve of approximately 40 hours. Reasonably decorated with perlage, Geneva stripes, and a signed rotor, the Landeron 24 is a solid option for a function-forward diver at this price point, and my limited personal experiences with this movement have all been quite positive. As I mention in my hands-on review of the Isotope Old Radium Bronze Tobacco, the Landeron 24 movements that Isotope uses are proper no-date calibers, meaning that they don’t have the irksome “ghost” position when you pull up the crown to set the time. Additionally, just like the HydriumX “The Judge,” the 22mm lugs of the new Hydrium Pro Nordblad are fitted with a black tropic-style FKM rubber strap that offers integrated quick-release spring bars and is completed by a signed stainless steel pin buckle.

Much like a significant portion of the brand’s watches, the new Isotope Hydrium Pro Nordblad will be produced as a limited edition of 100 pieces, and it will be accompanied by an official retail price of £900 GBP (which works out to about $1,110 USD, at the time of writing). Isotope’s prices automatically get converted to your local currency on the brand’s website in real-time, and this explains the rather unusual and exact values that can sometimes appear, depending on your specific shipping location. While the new Isotope Hydrium Pro Nordblad is slightly more expensive than most of the other models from the collection, the actual difference in price is very minimal, and this is likely a direct result of the additional oversight and internal testing required in order to ensure that the watches exceed the standards outlined by ISO 6425 specifications. Although Isotope’s funky and colorful design language isn’t always everyone’s cup of tea, the new Hydrium Pro Nordblad offers a significantly more utilitarian and traditional overall appearance, while still showcasing much of the same distinct design DNA that defines all Isotope watches. For more information on the Isotope Hydrium Pro Nordblad Limited Edition, please visit the brand’s website.

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