The year is 1981, and you’re lounging on the beach in Hawai’i on a much-needed vacation. As the sun scorches your skin and you begin to doze off into an afternoon slumber, you hear fellow beachgoers scream in excitement. Propping up on one elbow to have a better view of the commotion, you peer through your gloss-black Ray-Ban Wayfarers to see something that doesn’t look quite right. Standing 6 feet 4 inches tall with a mustache that is the stuff of legends is none other than Tom Selleck — or, as the crowd is screaming, “Magnum!” As he gracefully waves to fans, a glare from his wrist catches your eye, a glare that can only be his trusty Chronosport Sea Quartz 30 Dive watch. The capable and high-tech tool watch is the perfect pairing for the now-superstar private investigator. Fast forward to the present day, and Momentum Watches has revived the popular dive watch that was sold across North America starting in 1977 and graced Tom Selleck’s wrist for the first three seasons of Magnum P.I.

The new generation of the Sea Quartz 30 isn’t a run-of-the-mill vintage reissue. Momentum Watches is operated by the St. Moritz Watch Corporation, which has a direct lineage to the original family behind the Chronosport watches. This direct connection not only made the decision to revive the popular model easy but allowed the brand to send original parts to its manufacturers to ensure that an authentic reproduction was made. While the name on the new models has changed, the brand has retained the spirit of these analog quartz dive watches with just the right amount of upgrades.

Advertising Message

As with most of Momentum’s line-up, affordability is key. To celebrate the revival at the beginning of 2023, Momentum offered the Sea Quartz 30 at its original retail price of $195 USD. After the first run of watches, the price was increased, but not substantially. As a result, this fun, funky, and affordable dive watch has garnered plenty of affection and has been consistently sold out.

The Sea Quartz 30 comes in a 42mm-wide, 11.3mm-thick, and 47mm lug-to-lug stainless steel case mounted on an appropriately jangly brushed and polished jubilee-style bracelet or rubber tropic strap of your choice. The case is predominantly brushed on the top with polished chamfers transitioning into fully polished sides and caseback. The transitions between brushed and polished surfaces are not immaculate, with the polished edges bleeding over slightly, but it is not noticeable unless inspected closely. The caseback is solid steel with lightly engraved specs and room for your own engraving. Pointed crown guards project from the case at 3 o’clock, shielding the unsigned 5.9mm pillbox crown from impact without impeding its use. Despite the robust protection the crown guards offer, I have experienced no discomfort from the crown or guards flanking it. The screw-down crown aids in achieving a depth rating of 300 meters — far more than I will ever need.

Topping off the case is a polished coin-edge steel bezel with a luminous sapphire insert. The polished edges of the bezel create a slippery surface, making the bezel difficult to operate with wet hands and some gloves. I would like to see this texture improved for use while diving, but it is capable for my non-life-threatening tasks. The bezel features 120 clicks, is unidirectional, moderately stiff, and has a fully graduated elapsed time scale. A high-pitched ratcheting sound when rotated adds to the overall vintage vibe. The sapphire insert on the bezel and plays with the light and represents the bakelite bezels of its ancestors. Matching the bezel is a flat sapphire crystal over the dial.

Advertising Message

A highly legible matte-black dial stands in contrast to the flashy exterior case. Large, luminous block indices add texture and depth to the flat dial with quirky fonts used for three of the cardinal indices. A day/date function found at 3 o’clock matches the dial color. A small gap between the day and date wheels reveals part of the movement behind and breaks up the uniformity of the window, which I find needlessly distracting. However, considering the price point, it is certainly something I can overlook.

Momentum nailed the hands on the Sea Quartz. Often hand length is unbalanced in more affordable watches, but here they are just right. The fat orange minute terminates at the minute track and adds an additional playful touch while increasing legibility at a glance. It is paired with rectangular paddle hour and seconds hands that terminate before and after the hours markers respectively. All the luminous material on the dial, hands, and bezel glows brightly and has a toxic shade of green that is uncommon and adds to the vintage appeal.

Powering the Sea Quartz 30 is, you guessed it — a quartz movement — specifically, the Swiss Made high-torque R507 Ronda movement. These reliable quartz movements have a 45-month battery life and are rated for -10/+20 seconds per month. While not the cream of the crop when it comes to quartz calibers, it helps keep the price down significantly.

On the wrist, the Sea Quartz 30 wears flat with a slight downturn of the lugs hugging the wrist. Paired with the brand’s tropic-style straps, the watch is begging to be taken on an adventure. The tropic-style straps are also surprisingly supple and comfortable, unlike most other similar straps I have tried. The jubilee bracelet features solid links throughout with pushpins for sizing and a milled flip-lock clasp. Six micro-adjustments in the clasp are a pleasant addition for achieving the perfect fit. Throwing the Sea Quartz 30 on a NATO-style strap also scratches that military navy dive watch itch that I seem to get every time the weather warms up.


Some watches simply bring us joy. For me, the Momentum Sea Quartz 30 is one of those watches. It is a quirky vintage-inspired offering that feels like something I might stumble upon in the depths of eBay searches, except the modern materials make it a watch that I don’t need to worry about taking to the beach. Additionally, the affordable price point makes it something I wouldn’t worry about getting a few scratches on. As you can see from the photos in this review, I have worn it quite a bit. The Sea Quartz 30 has quickly become my grab-and-go daily wear and will continue to be on my wrist for summer 2023. A stiff slippery bezel and a small gap in the date window are minor concessions to make in a $295 USD watch. While the sold-out stock has plagued this fun affordable diver since launch, the brand has made a consistent effort to restock, open multiple pre-orders, and has teased more versions to come, including a full DLC case and bracelet and a solar quartz variant. While the Sea Quartz 30 won’t make you as cool as Tom Selleck in Magnum P.I., it certainly can make you feel like you are. Learn more about Momentum Watch and the Sea Quartz 30 at the brand’s website.

Necessary Information:
>Brand: Momentum
>Model: Sea Quartz 30
>Price: $295 USD
>Size: 42mm-wide, 11.3mm-thick, 47mm lug-to-lug
>When reviewer would personally wear it: To the beach/pool/boat, during physical activity or sports.
>Friend we’d recommend it to first: A friend who’s interested in vintage watches but is concerned about damage, water intrusion, and service costs
>Best characteristic of the watch: Funky dial font and nuclear lume
>Worst characteristic of the watch: Stiff and slippery bezel

Advertising Message

Subscribe to our Newsletter