Image by Christian Weber Shutterstock

The thermal pool at Terra Nostra Garden in Furnas, Sao Miguel, doesn’t look particularly appealing at first sight. But don’t let the murky brown colour put you off – it comes from the iron dissolved in the water gushing from a volcanic spring at 35C to 40C, the perfect temperature to ease sore limbs after a strenuous hike.

Such springs dot these islands, but the Valley of Furnas is a hotspot of geological activity even by rarefied Azorean standards. The valley, which is in fact a huge volcanic crater, first became popular in the 18th century thanks to growing interest in the healing power of the mineral-infused water.

There are several other places where you can bath in Furnas, but the pool at Terra Nostra is the largest and most famous option; built in 1780 by a wealthy American expat and enlarged in 1935, it forms the centrepiece of a sublime subtropical garden, which all adds up to a profoundly restorative experience.