Ten spa and hot-spring escapes to switch off together

There is a particular kind of holiday conversation that only happens in warm water: unhurried, slightly absurd, better than anything achieved across a dinner table. Thermal towns have understood this for millennia, which is why the Romans, the Habsburgs and the samurai all built their pleasure architecture around a hot spring. The ten escapes below range from marble grandeur to volcanic riverbanks, but the prescription is identical everywhere — soak, wrap up, eat well, repeat. Leave the itinerary at home; it dissolves in the steam anyway.

The Black Forest's belle-époque spa capital, where Dostoevsky gambled and Queen Victoria took the waters. The Friedrichsbad runs a nineteenth-century ritual of seventeen stations of steam, scrubs and plunge pools; the Caracalla next door is the modern, swimsuited alternative. Walk the Lichtentaler Allee's riverside gardens between soaks, and dress up for an evening at the Kurhaus casino — the prettiest in Europe, and worth it just for the chandeliers.

Britain's only natural thermal waters, bubbling up at a constant 45 degrees beneath a city that is itself a Georgian spa set in stone. The modern Thermae complex crowns it with an open-air rooftop pool overlooking the abbey — book the last evening session, when steam rises against the floodlit towers. Pair it with the Roman Baths by day (look, don't touch) and a night in a Georgian townhouse hotel.

Budapest is the only capital sitting on over a hundred thermal springs, and it built palaces over them. The Széchenyi's canary-yellow courtyard pools steam gloriously in winter, chess players soaking mid-game; the Gellért is the art nouveau jewel, all turquoise tiles and stained glass. Do one of each, go on a weekday morning to dodge the crowds, and thaw out afterwards with chimney cake and mulled wine.

A hillside of white travertine terraces filled with milky-blue thermal water, with the ruins of Roman Hierapolis on top — spa tourism, two thousand years early. Swim among submerged marble columns in the Antique Pool, allegedly a gift from Antony to Cleopatra. The site floods with day-trippers from the coast by mid-morning, so stay overnight in Pamukkale village and walk the terraces barefoot at opening time or sunset.

Ninety minutes from Tokyo, Hakone is Japan's classic onsen retreat: forested mountains, a lake with torii gates at the waterline and — on clear days — Mount Fuji presiding over everything. Book a ryokan with a private open-air bath, since most public onsen separate the sexes, and surrender to the rhythm of soaking, kaiseki dinners and yukata-clad idleness. November brings autumn colour and the sharpest Fuji views.

In deep southern Tuscany, sulphurous water at 37 degrees tumbles over the Cascate del Mulino's tiers of natural travertine pools — free, open around the clock and gloriously pagan. Arrive at dawn or after dark to have the steaming cascades to yourselves; summer weekends get busy. Those wanting robes and treatments can book the Terme di Saturnia resort next to the spring itself, then eat wild boar pici in nearby Montemerano.

Milky geothermal water at 38 degrees in a black lava field, steam drifting over silica-smoothed rocks — Iceland's most famous soak is unapologetically touristy and doesn't care; neither will you. Book the evening slot in winter, when floodlit steam and the chance of northern lights turn the lagoon frankly cinematic. Stay at the Retreat for access to the quieter private lagoon, and slather on the complimentary silica mud mask — the romance will survive it.

The Habsburg empire's favourite spa town, a wedding-cake canyon of colonnades and pastel facades where Beethoven, Goethe and half of nineteenth-century Europe took the cure. Sip the hot mineral water from a porcelain spouted cup as you promenade — it tastes medicinal, which is rather the point — then book a proper treatment at the Alžbětiny Lázně baths. Stay at the Grandhotel Pupp, an inspiration for Wes Anderson, and come in autumn when the wooded hills turn copper.

New Zealand's geothermal heartland steams, bubbles and occasionally erupts around a lakeside town that smells faintly of sulphur and doesn't apologise. Soak in the Polynesian Spa's lakeside pools as black swans drift past, then day-trip to Wai-O-Tapu, where the Champagne Pool rims orange like a science-fiction cocktail. Book an evening at a Māori cultural village for a hāngī feast. Go in the southern winter, June to August, when the cool air makes the hot pools sing.

Steaming outdoor water at 1,585 metres with the Canadian Rockies filling every sightline — the Banff Upper Hot Springs have been thawing travellers since 1886. Winter is the masterstroke: sit in 39-degree water while snow settles on your hair, then retreat to the baronial Fairmont Banff Springs for cocktails beneath the turrets. You may share the drive up with elk; give way graciously. Book January for snow-globe conditions and skating on frozen Lake Louise nearby.