We all know that a finely engineered mechanical wristwatch is more than just a tool for telling the time. It’s also a celebration of craftsmanship for craftsmanship’s sake. Indeed, part of the appeal of these machines is that they are far more complicated than they have any reason to be. This is especially true of one timepiece: the perennially popular diving watch. Built to withstand sub-aquatic pressures that few who wear them are likely to ever encounter, they nonetheless serve as a powerful statement.

“Mechanical Swiss dive watches transcend their purpose and represent a derring-do that’s largely absent in our modern lives,” says Mr Jason Heaton, dive-watch authority for Gear Patrol and an experienced diver himself. “It’s akin to the booming popularity of workwear clothing and 4x4 SUVs, all allowing men to recapture a bit of the adventurous spirit from the golden age of exploration.”

It was the trench warfare of WWI that first demonstrated the hands-free utility of the wristwatch over the pocket watch. But during the inter-war years, civilian wearers discovered that they had a tendency to need servicing much more often, since the gears got clogged with dust or the mechanics started to rust. What was needed was a waterproof case. This presented watchmakers with a problem. How to seal up the wristwatch’s Achilles heel, the winding crown, without sealing the whole thing in a secondary case, negating the handiness of a wristwatch in the first place?

As with most things horological, it was Rolex to the rescue. Its revolutionary Oyster case of 1926 featured a winding crown that could be screwed against the middle case to create a watertight seal. A hermetic system so elegant that it’s barely changed since, save for the introduction of tighter “O-ring” rubber gaskets and brighter luminous markings, the Oyster marked an important milestone in the history of the waterproof watch.

But it wasn’t the first true diving watch, at least not by modern standards. True diver watches have their own ISO standard, number 6425. Introduced in 1996, it demands – among many other exacting criteria – at least 100m water resistance, the ability to time dives up to an hour by aligning a rotating bezel with the minutes hand, legibility in the dark from a distance of 25cm and, in case the watch is battery-powered, an end-of-life indication (your watch’s life, not your own).

Note here that the so-called “water resistance” of any watch, not just diving watches, is the depth the watch can go without water leaking in – but only under perfectly still conditions. In reality, flailing your arms around underwater creates eddies around the case’s joins and junctures, adding to the water’s pressure. So your 30m dress watch will survive a light rain shower at best. A 200m diving watch is good enough for your average bit of scuba; anything above that is a simple matter of reassurance or gadgetry for the sake of it, seeing as a human body wouldn’t survive the crushing pressures deeper than 300m.

“Let’s face it, diving watches are uncomplicated creatures,” says Mr Heaton of the genre’s modern era. “The specs of the original divers of the 1950s would still do fine today. Watchmakers are irrepressible tinkerers, though, hence the ever-more absurd depth ratings of Rolex’s 1,200m Deepsea or Bell & Ross’ 11,100m Hydromax back in 1997. But again, it’s a talking point at the water cooler on Monday morning.”

These watches also happen to be the perfect choice of wristwear when you finally escape Monday morning for sunnier climes. Even if you lack a taste for open water, let alone Padi certification, a diving watch means you can plunge straight into the hotel swimming pool without even thinking about it; or splash off the sand from a day’s sunbathing without a care.

Plus, a diver’s versatile cool factor means it will easily straddle beach and beach bar effortlessly. If the watches sitting around the boardroom table are invariably divers by design (see almost every top-selling Officine Panerai, Omega or Rolex), then you’ll certainly get away with wearing one for sundowners.

In increasing order of water-resistance, then, here are seven diving watches to accessorise with your Vilebrequins.

NOMOS Glashütte is a pragmatic brand with a sideways sense of humour – hence the fact that its very first water-resistant piece was pitched as a swimmer’s, not diver’s, watch. Its strap is even inspired by the woven bands that hold your municipal pool’s locker keys. NOMOS’ designers being located in Berlin (while its watchmakers beaver away deep in the Saxon mountains), the rest of the Ahoi Atlantik is sublimely designed, pumping up the brand’s signature Bauhaus aesthetic just enough to feel fit for splashing about, setting things off with a sumptuous blue dial and piercingly luminous hands that practically smell of chlorine. In a good way.

It may be better known for its conquest of the skies, thanks to a flurry of chronograph innovation in the first half of the 20th century, but Breitling has serious form beneath the waves, too. Its Superocean also has pedigree, dating from as far back as the late 1950s. Relaunched to industry-wide raptures in 2007, the retro-in-feel, but most certainly modern-in-build collection is now a catalogue fixture. This super-precise “chronometer” certified model will be at home with the fish, thanks to 200m water-tightness and a tough-as-old-flippers Diver Pro II rubber strap. But instead of luminous “Super-LumiNova” markings, a judicious sprinkling of red gold makes the Héritage Superocean II B20 better suited to the teak deck of your yacht, the evening’s first G&T in hand.

Aquatimer is a diving-watch range that’s been going strong since 1967. All the enduring codes of sub-aqua time telling had been coined, with commercial and research divers demanding the most of their instruments. This made IWC Schaffhausen’s Aquatimer reboot of 2016 doubly impressive as the brand managed to invent a properly useful new external/internal rotating bezel, which combines the aesthetic elegance of an inner bezel, connected via a clever sliding clutch to an outer bezel that’s easy to twiddle while wearing neoprene gloves. As with all proper diving watches, the bezel only moves anticlockwise, ensuring that, even if you were to accidentally knock the bezel during a dive, your resurfacing time will simply come sooner, rather than be dangerously overshot.

Back in 1997, Parisian startup Bell & Ross scored a place in The Guinness Book Of Records with its Hydromax: proven water-resistance all the way down to an unprecedented 11,100m. Why not a rounded-down 11,000m? Simple: the deepest place on Earth is the Pacific’s Mariana Trench, which is 11,035m. Waterwings thus unanimously earned, Bell & Ross has since established itself as a fashion-forward watchmaker favoured as much by military professionals as rollnecked architects. Its square-cased instruments may be inspired by cockpit readouts from fighter jets, but the looks are just as suited to the hyperbaric suits of oil-rig welders – and just as technically advanced given the Diver’s 300m rating, as water pressure acts unpredictably around a non-circular joint.

Florentine naval equipment supplier Officine Panerai was, despite its esoteric origins, a diving-watch frontrunner in the 1930s. The family firm recruited Rolex to make them a limited, and now highly collectable, run of cushion-shaped pieces for the Italian Navy’s elite, covert frogmen, adorned with Panerai’s patented luminous paint – the originally radioactive Radiomir, followed by the rather less lethal Luminor during WWII. Now in the hands of luxury powerhouse Richemont, Panerai’s iconic, voluptuous cushion shape has endured, as well as underwater performance – though with less emphasis on attaching limpet mines to Allied battleships. Even if you were to indulge in such antisocial activity, the mechanics inside this particular Submersible would be unaffected by the mine’s powerful magnet as it’s protected by a soft-iron core.

A claimed 500m diving watch with a hole deliberately drilled into the crystal dome doesn’t sound too promising at first, but it’s cleverer than you think. Pioneering a revolutionary new means of indicating your dive depth, yet still maintaining Oris’ value for money, its Swiss boffins have carved an air channel around the dial, into which sea water enters as you descend into the murky blue. As pressure increases, the air-water “meniscus” interface is pushed further around the channel, acting as a marker against the depth calibration. Simplicity itself from typically elegant Oris.

Henley-on-Thames’ plucky watchmaker turns from the skies to the waves here, with a fresh new take on a collection named after the 1930s aircraft company, Supermarine, whose 1930s’ Type 300 waterplane won the Schneider Cup and was part of the lineage that led to one of Britain’s most iconic aircraft, the Spitfire. Limited to just 300 pieces, the Waterman has already been tested in the most extreme ocean environments by brand ambassador Mr Mark Healey – world-renowned free-diver, big-wave surfer and environmentalist. Extra pub-bore points are won thanks to its helium escape valve – first introduced by Rolex for its commercial Sea-Dweller model, made public in 1969 by Doxa. It’s rather useless to Mr Healey, but essential for industrial divers who spend days on “saturation” dives, eating and sleeping in pressurised diving bells. The air mix contains helium, whose atoms are tiny enough to leak into even the tightest watch case. Without a special valve, the helium can’t escape quickly enough on depressurisation, popping the dial’s crystal out.