Hands-On: the Isotope Hydrium California

Isotope initially piqued my interest two years ago with their uniquely design-forward Hydrium “Will Return” dive watch. This timepiece was intentionally crafted to resemble the iconic “Will Return” sign often seen in shop windows, and its “Why not?” approach left a lasting impression on me. 

Fast forward two years, and Isotope, founded in 2016 by José and Joana Miranda and headquartered in England, has expanded its Hydrium line with the Hydrium California. This watch, like its predecessors, boldly defies the conventions of typical dive watches, drawing inspiration from Isotope’s own heritage as much as from classic dive watches from the past century. 


Hands-On: the Isotope Hydrium California

Stainless steel
Landeron Automatic
FKM Rubber
Water Resistance
300 meters
40 x 48mm
Lug Width
Screw down

When the Hydrium Califonia first arrived the first thing I noticed was its case. The starkly uniform bead-blasted finish, which reduces the risk of unwanted reflections that may attract predators during ocean adventures according to Isotope, immediately let me know I could expect this quirky dive watch to be utilitarian not only by design, but also in practice. 

I eagerly strapped it to my wrist and, despite its generous thickness of 14.9mm, including the double-domed Sapphire Crystal, was pleased to learn that it wears true to its 40 mm diameter size thanks to blockish lugs allowing for a reasonable lug to lug of only 48mm. Fitting for its hefty presence, this unconventional diver boasts a very conventional 300 meters of water resistance. As I peered through the display caseback I was met with blued screws, a custom rotor, and perlage. The smooth hand winding of the Swiss Landeron inside did not disappoint, operating with a butteriness one would expect from a movement finished to this level.

My kids often offer spot-on observations when they spy a new watch on my wrist. And so, I wasn’t surprised to hear my daughter accurately exclaim that the “the dial looks like foam!”, immediately noticing the Istotope’s shimmering grainy dial texture, reminiscent of styrofoam. If she had used a loupe, she would have noticed that this texture seamlessly integrates with the raised numerals, each featuring a subtle touch of “foam” on their sloped edges. This texture offers a unique approach to the ever-popular California dial (a combination of half Roman and half Arabic numerals, designed to be easily readable in low-light conditions) and demonstrates Isotope’s knack for adding flair where it’s least expected.

Another striking feature found below the crystal are the bold hands with their industrial-style brushed finish, which doesn’t require a loupe to appreciate. As I watched the ideal-length hour and minute hands reach their intended marks, I noticed they weren’t perfectly cut and had a slightly jagged appearance- an unexpected yet welcome touch proving that while this watch may draw inspiration from the California dials of Rolexes and Panerais from decades past, it refuses to be a mere homage.

Beyond the dial, the 120-click bezel is divided into five-minute segments, a choice that gives the watch a vintage feel while still retaining the practicality of a timing bezel for daily use. I’m not a diver and tracking elapsed time with precision is not a top priority for me. Over the course of a week, I learned that my life generally happens in five-minute increments and never found myself inconvenienced by the simplified layout. I timed 30-minute lunch breaks and 10-minute pasta with ease. When I made the fancier pasta that cooks in nine minutes, thankfully I was smart enough to do the math with the ease of the Hydrium’s blocky minute hand expertly reaching the outer minute track.

Spaghetti needs aside, due to the notable width of this hand and the fact that its size exceeds an actual minute on the outer track, I was surprised to find myself challenged to read the exact time on occasion- a problem I’ve previously only experienced with one-handed watches. Would I ask Isotope to substitute for a thinner hand? Absolutely not. The current hands expertly capture Isotope’s hallmark blend of inviting brutalism. Exact time be damned, please don’t take that away from me.

In addition to the unexpected details such as the plentiful texture, I found myself enjoying how Isotope incorporated its signature shape, the Lacrima, thoughtfully into the design of the Hydrium California. Discovering this subtle tear drop shaped branding scattered throughout the watch became a fun game, like a child discovering unanticipated Easter eggs. The rotor, crown and the base of the second hand all bear the brand’s mark without overwhelming the overall aesthetic.


The rugged industrial motif of the Hydrium California carries seamlessly from the bead-blasted case to the brushed hands. And so, with the overall aesthetic tied together impressively well, anything out of place is destined to stand out- which led me to discovering my only gripe: the nearly-matching colors on the bezel, dial, and hands. Color matching is not a hill I will die on, and things like white date wheels don’t keep me up at night. However, the Hydrium California contains stark white text on the dial, off-white bezel markings, olive green indices, and beige luminous painted hands. I couldn’t help but find myself wishing for some, even a couple, of the components to match. It’s a minor detail, but when a dial begs to be admired as this one does, the last thing I want is a distraction.

As an enthusiast on a budget, watches in my personal collection tend to float around the $500 range. It’s a price point where you can get a lot of value for the dollar, but can also count on some predictable compromises: no-frills movements void of decoration, finishing that is perfectly subpar, and straps that are almost always worth replacing with a third-party option. Isotope makes it easy to see how far some additional dollars will go. Beyond the blued screws and a loupe-friendly dial, you’ll be hard-pressed to find a more comfortable stock strap than the provided 22mm quick-release black FKM that comes with the Hydrium California. It’s easily the most comfortable stock strap I’ve experienced- notably supple to the point of having a leather-esque quality, and never once did I have an issue with the strap escaping its keepers, often a constant battle with other rubber straps.

Two years from now, I predict the Hydrium California will remain on my mind, just as the “Will Return” diver has. It’s a watch that represents the best of Isotope’s signature brutalist industrial design and makes a statement while still lending itself to practical daily use. Isotope

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Nathan Schultz is a New Hampshire based writer, equally obsessed with watches and outdoor gear. He specializes in dad jokes, breaking NH35s while modifying watches, and testing the limits of recreational equipment. Micro brands hold a special place in his heart, and he aspires to stop buying and selling so many darn watches.