Any diver who really needs to know their depth is also unlikely to trust a mechanical system integrated into their wristwatch – if only for how difficult it is to read on such a tiny scale. And then there is the helium escape valve. The least understood, nearly always unnecessary, but by no means most useless function found on nearly every luxury diving watch.

It was invented by (you guessed it) Rolex in the late sixties, for its beefed-up ‘Sea-Dweller’, and essentially allows accumulated helium gas to escape the watch during decompression. It’s a fancy addition, totally unnecessary for daily wear, but also quite cool.

The Best Diving Watches You Can Buy Right Now

Seiko Prospex Turtle Save the Ocean

The name ‘Cousteau’ is synonymous with the life aquatic, and it’s the grandson of fifties pioneer Jacques-Yves who perpetuates the family tradition today.

The Fabien Cousteau Ocean Learning Centre and by default the Earth’s greatest resource now directly profits from its new partnership with Japan’s watchmaking giant Seiko – a brand whose Prospex range embodies a continuous lineage of super-affordable and ever-evolving diving watches since the sixties.

This one’s good to 200m with precision mechanics and a bang-on-trend gradient dial thrown into the bargain. Buy Now:

Longines Heritage Skin Diver

The museum at Longines’ St Imier HQ is a near-bottomless inspiration for the venerable brand’s ongoing ‘Heritage’ collection – a line kickstarted in 2007 with the now-cult-collectible (no-date-display) Legend Diver.

This latest Heritage revival goes even further back, reviving the very first Longines diving watch of 1959, but going even deeper down – to 300 meters’ water resistance. The flawless gleam of that black-PVD-coated bezel just begs to be twizzled at first sight. Buy Now:

Omega Seamaster Diver 300M

Launched in 1948, the Seamaster line was Omega’s first official “family” of watches. Modeled on the “Watch. Wrist. Waterproof.” MoD-spec pieces made for Allied troops, it was soon ramped up to Submariner-matching 300m water resistance in 1957.