Spas aren't just the preserve of posh hotels. All these springs are open to the public and though some are simple pools in fields, others architectural marvels, all offer water heated by nature alone
Peter Zumtor's Therme Vals in Switzerland is Europe's trendiest natural hot spring Photograph: Christof Sonderegger/PR
1 Landmannalaugar, Iceland
The milky waters of the Blue Lagoon are an iconic image of Iceland, but for something less crowded and more natural, make for Landmannalaugar (landmannalaugar.info) in the centre of the island. It's inaccessible in winter, but by summer the road is clear and hikers arrive to soothe their muscles with a quick dip in the geothermal waters that feed into local brooks. Hire cars are forbidden to drive here, but there are regular buses from Reykjavik from mid-June to mid-September.Stay: Landmannalaugar Hut sleeps 110 (bring your own sleeping bag) and costs around 2,200 krona (£13.50) per night or there is a campsite nearby (00 354 854 1192, July to September only)
2 Hveravellir, Iceland
Another slice of unadulterated nature in Iceland. Hveravellir (00 354 452 4200; hveravellir.is), means "hot spring plains" and is a nature reserve bracketed by two glaciers. It's popular with hikers and riders. There's a hot pool near one of the huts but the geothermal water also feeds into nearby streams for more temperate bathing.Stay: Hveravellir Lodge (00 354 894 1293; hveravellir.is), dormitory beds from 3,500 krona (£21.60), double rooms from 10,000 krona per person (£61.70)
3 Matlock, Bath, Derbyshire
More pleasingly warm than piping hot, the 18th-century indoor swimming pool at the New Bath Hotel (01629 583454; brook-hotels.co.uk) in Matlock Bath is filled by thermal waters. There's also an outdoor swimming pool fed by the spring, which is open from May to October. A day pass for both pools costs £5 for adults and £2.50 for children.Stay: Hurdlow Grange (07866 778847; hurdlow.co.uk) has three-night breaks in a cottage sleeping six from £456