The Isotope Hydrium Pro Nordblad is a 40 mm automatic dive watch made in a limited run of 100 to honor Finnish ice diver Johanna Nordblad. Isotope specifies 300 m water resistance and says the watch exceeds ISO 6425, but that is the manufacturer’s claim—not evidence that each watch was independently tested or certified. The model is listed as sold out, so its published prices are historical rather than current offers.
What is the Hydrium Pro Nordblad?
Isotope describes this as its first Hydrium Pro and a 100-piece limited edition created as a tribute to Johanna Nordblad. The brand’s account says Nordblad swam 50 meters beneath ice between openings in 2015 while wearing a swimsuit, then swam 103 meters under ice without fins in March 2021, also wearing a swimsuit. These details are Isotope’s account of her achievements. The brand also references the Netflix documentary Hold Your Breath: The Ice Dive. Isotope’s product page
Case size and wrist presence
The manufacturer lists a 40 mm case diameter, 48 mm lug-to-lug length and 12.9 mm case height. Height increases to 14.9 mm when the double-domed sapphire crystal is included. The lugs are spaced 22 mm apart.
Fratello’s July 2023 reviewer described the watch as substantial but wearable on his roughly 17.5 cm wrist, with some room to spare. That is one person’s fit impression, not a guarantee for other wrists; the crystal-inclusive height is also worth considering if you prefer a low-profile watch. Fratello’s hands-on review
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- Stainless Steel case with Black Resin Band
- Black Dial with date window at 3 O'clock
- Luminous markers and hour hands; sweep second hand
- Anti-reverse bezel
- Water-resistant to 200 M (660 feet)
Design and dive-watch specifications
Isotope specifies a micro-blasted 316L stainless-steel case, matte black dial, bold white Arabic numerals filled with Super-LumiNova, and the brand’s “i” hands. Sapphire crystals cover the dial and exhibition case back. The black FKM rubber strap has quick-release fittings, and the bezel is unidirectional with 120 clicks.
| Specification | Isotope’s listed detail |
|---|---|
| Water resistance | 300 m / 30 atm / 1,000 ft |
| Movement | Automatic Swiss Landeron |
| Power reserve | 40 hours |
| Jewels and frequency | 25 jewels; 28,800 A/h |
| Stated accuracy | -12/+12 seconds per day |
| Bezel | Unidirectional, 120 clicks |
| Strap | Black FKM rubber, quick-release, 22 mm |
These are manufacturer specifications, not measurements from independent testing for this article. Fratello’s reviewer noted the bezel’s lume and indexation and characterized the design as function-forward; those are the reviewer’s observations rather than test results.
Rank #2
- The waterproof level of this watch has reached 10 ATM waterproof, which can work normally at a depth of 100 meters (330ft) underwater. It is not only suitable for wearing in water activities such as swimming, diving, snorkeling, surfing, rowing, water skiing, but also suitable for wearing in daily life and outdoor sports, such as jogging, hiking, climbing, cycling, etc.
- The built-in stopwatch and timer function of the watch can meet the precise timing needs of exercise and sports competitions.
- The dual time zone display function will make your trips more convenient; 12/24 hour format display can meet the time reading habits of different people.
- Support multiple useful functions, such as: alarm clock, hourly chime, calendar and back light.
- The watch battery is replaceable. If you find that the watch is not working or the text on the display is not clear, please replace the watch battery in time.
Does it meet ISO 6425?
Isotope says the Hydrium Pro Nordblad’s specifications exceed ISO 6425, the standard for dive watches. That statement should not be read as independent ISO certification. Fratello explains that ISO sets requirements rather than certifying individual watches and cautions that a brand’s claim does not establish that every piece underwent independent testing. Buyers who require documented testing should ask Isotope what evidence is available for this specific model.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Price and availability
Isotope’s product listing displays the model as sold out, and its Hydrium archive includes the watch. New-stock availability is therefore unconfirmed; check with the brand for current status. Secondhand availability depends on the market, and no current resale listing or price is established here. Isotope also notes that import taxes and duties depend on the buyer’s destination, so any applicable costs need to be checked for the relevant order and location. Isotope’s Hydrium archive
Rank #3
- 330 ft. (100 M) water resistance. In general, suitable for recreational surfing, swimming, snorkeling, sailing and water sports.
- 12/24-hour timekeeping, 43 mm resin case with mineral dial window, Japanese quartz movement; Analog: 3 hands (hour, minute, second)
- Case / bezel material: Resin; Rotating bezel
- Day and date display at 3 o’clock
- Analog display, molded resin band with buckle closure; Accuracy: ±20 seconds per month
| Published price | Source and context |
|---|---|
| £1,080 | Fratello Watches, July 2023; historical price reported in its hands-on article. |
| £900 | WatchPro, April 2023; launch-era price, not a current quote. WatchPro launch coverage |
Launch-era publications reported differing prices, which may reflect publication timing, currency conversion or tax context. Neither figure establishes what the watch costs today.
Quick Recap
Best Value
- Iconic Promaster watches with advanced functions designed to venture to the deepest depths.
- 3 Hand, Date
- Silver-Tone Stainless Steel
- Luminous Hands and Markers and Mineral Crystal
- Sustainably powered by any light, with our Eco-Drive technology this watch never needs a battery. ISO Certified, 200M Water Resistant and 5 Year Limited Warranty
Rank #4
- DIVER-INSPIRED DESIGN — Inspired by the sea, the MDV-106B is styled after classic dive watches and delivers 200-meter water resistance at an unbeatable price point. The black resin band and stainless steel case give it a classic look, while the anti-reverse rotary bezel adds authentic dive-watch character.
- STAINLESS STEEL CASE WITH SCREW-LOCK CROWN & CASEBACK — The MDV-106B features a stainless steel case and a reliable screw-lock crown for enhanced water resistance protection. Screw-down crown and screw-lock caseback work together to keep the movement sealed and secure during water activities — a construction standard found on dive watches far above this price range.
- LARGE FLUORESCENT HANDS & INDICES FOR INSTANT READABILITY — The dial features hands and hour indices with large fluorescent areas for easy reading in low-light and underwater conditions. The clean 3-hand analog layout with date display at 3 o'clock keeps the dial uncluttered and immediately legible at a glance.
- 44MM STAINLESS STEEL CASE | 22MM LUG WIDTH | MINERAL GLASS — The case measures 44mm in diameter, 12mm in height, with a 49mm lug-to-lug length and a standard 22mm lug width — making strap upgrades effortless with a vast range of aftermarket options. Mineral glass protects the dial from everyday scratches and impacts.
- 3-YEAR BATTERY & 200M WATER RESISTANCE — Powered by an SR626SW battery with an approximate 3-year life, the case measures 49.5 × 46.3 × 12.1mm and weighs 92 grams. At 200 meters of water resistance, the Duro is versatile and suitable for all situations — whether in the water, hiking, running, or at the office.
What to check if you are considering one
- Fit: Compare your preferences with the 48 mm lug-to-lug length and 14.9 mm crystal-inclusive height, not just the 40 mm diameter.
- ISO documentation: Treat “exceeds ISO 6425” as Isotope’s claim unless the brand supplies supporting test documentation.
- Movement expectations: The -12/+12 seconds-per-day accuracy is the manufacturer’s stated specification, not a measured result for a particular watch.
- Replacement straps: Isotope lists a 22 mm quick-release FKM strap. Before buying a replacement, confirm lug width, spring-bar or quick-release compatibility, and return terms; the listed dimensions alone do not establish that a particular replacement will fit.
- Purchase status and price: Verify current stock and any secondhand listing, condition and asking price directly; the historical launch prices above are not current market valuations.
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
