Explorer Fabien Cousteau spotted wearing a Seiko

The wrist of Fabien Cousteau — ocean conservationist, documentary filmmaker, and heir to the most storied name in marine exploration — carries a watch that means business in the water. Spotted at what appears to be an aquarium or marine science event, Cousteau is wearing a Seiko Prospex automatic diver with the unmistakable profile of the so-called 'Baby Tuna' or 'Monster' generation, identifiable by its shrouded case construction, aggressive bezel, and trademark arrow hands.

The dial reads 'Automatic / Diver 200m,' which pins this squarely within the Seiko Prospex SRP6xx or SRPA2x family — most likely the SRPA21K1 or the closely related SRP637K1. Both share Seiko's calibre 4R36, a self-winding movement with manual winding capability, hack seconds, and a 41-hour power reserve beating at 21,600 vph. The case measures 47.5mm lug-to-lug with the protective crown-guard shroud, making it a substantial tool watch rather than a fashion statement. ISO 6425 dive certification at 200m rounds out the functional résumé.

The Baby Tuna occupies a unique position in the collector ecosystem: it delivers genuine professional dive credentials at an entry-level price point, yet its design DNA connects directly to the full-size Tuna (SBBN), which has been a staple of Japanese commercial diving since the mid-1970s. The shroud construction, while lighter than the Tuna's resin or titanium shell, gives the Baby Tuna its architectural character and remains immediately recognisable on the wrist. Steel bracelet variants are the most collected configuration.

For Fabien Cousteau — who in 2014 spent 31 days living aboard the Aquarius underwater habitat, surpassing his grandfather's record — a 200m-rated Seiko is not aspirational costuming. It is a credible working instrument. His choice of this accessible Japanese tool watch over haute horlogerie speaks to a functional ethos that mirrors his scientific work.

On the grey market, the Baby Tuna in steel trades well below its original retail, making it one of dive-watch collecting's most honest value propositions. A new generation of buyers continues to discover it through exactly this kind of authentic, unpretentious wear.