There was a period in the early 2010s, when it seemed as though watch brands were competing to see who could take up the most wrist space: 45mm cases relinquished bragging rights to 48mm and even 50mm timepieces – designs so large few could wear them with any degree of elegance. But times as well as tastes change. The preference for discreet luxury combined with the vintage revival saw case sizes slowly diminish, with 39mm and even 36mm becoming the new norm.

When Tudor launched its Pelagos in 2012, it was a tool watch with a substantial 42mm case. No delicate 39-ers here. There were some design flairs – the snowflake hands and pointy crown guards nod to the Submariners from the 1960s, the three-dimensional rehaut (the internal ring between the dial and the sapphire crystal) out of which the indices extended onto the dial – but this was a watch created for divers, particularly saturation divers. It had a water resistance of 500m, a helium escape valve, and a bracelet that could be easily micro-adjusted, as well as a patented self-adjusting spring-loaded clasp. This allowed the bracelet to respond to changes in the wrist as you dive; contracting as you go deeper and expanding as you surface – a watch for business, if your business happened to be diving, not really one for pleasure.

This year, Tudor has unveiled a Pelagos that is most definitely for pleasure. The brand has been playing with smaller case sizes for its Black Bay, taking it down to a positively dainty 31mm, so speculation was rife that it would do the same for the Pelagos. And that’s exactly what it’s done with the new 39. So, what’s changed apart from taking three millimetres off the case? The reduced water resistance – 200m as opposed to 500m – means there’s no need for a helium escape valve. This has allowed the case to be slimmed down from 15mm to 11.8mm, which means it can now slip neatly under a cuff.

There’s no date, the crown is smaller and, rather than a three-dimensional rehaut, it is now just a simple 45 degree-angled ring. The whizzy expandable clasp has gone; however, the T-fit adjustment system remains, allowing the wearer 8mm leeway over five different positions. There’s also the option of a rubber strap, should you want something more “weekend in the water” than “48 hours in the city”. Powering this new Pelagos is the MT5400, with 70 hours of power reserve, which first debuted in the Black Bay 36 that Tudor unveiled at this year’s Watches and Wonders and is made in Tudor’s Le Locle-based Kenissi manufacture.

Despite the changes and the ads featuring long-limbed women lounging by poolsides, the Pelagos 39 is still a dive watch. It’s just ditched the wetsuit in favour of a swimsuit, or pair of trunks – less dive support vessels, more sunning on yacht decks; an aesthetic emphasised by the sunray, rather than matt, dial. By taking the practical aspects that made the original Pelagos so popular and filtering them through a style-focused lens, Tudor may well have created the most desirable diver on the market. For now.

£3,500; tudorwatch.com