Thermal Water Pools (Caldeira Natural Monument)

Caldeira Velha is a small, enclosed valley on the northern slopes of the Fogo volcano, in the municipality of Ribeira Grande on São Miguel, and the springs here have been protected as a natural monument. It is one of the most atmospheric places on the island for a thermal bath, because the pools sit within dense subtropical forest, so that you soak in warm, rust-coloured water surrounded by tree ferns, ginger lilies, mosses and dripping vegetation, and the sound of a waterfall rolls through the trees. The experience is more like bathing in a jungle than in a spa.

The geology behind it is the same as at Furnas: the volcano still holds heat deep below, and water that seeps down is warmed and enriched with minerals before rising to the surface. At Caldeira Velha, the water is rich in iron, which stains the rocks reddish-orange, and it carries a hint of sulphur. The temperature of the main pool is pleasantly warm, around the upper thirties Celsius, while the waterfall pool upstream is much cooler, because it is fed partly by a cold stream. Moving from one to the other is part of the experience, and some people alternate for the contrast.

To protect the site, entry is managed. Visitors are admitted in timed shifts, with a limit on the length of the stay, usually around an hour and a half, and capacity is capped, so on busy days the waiting time can be long. The best strategy is to go early in the morning, when the first shift begins and the light filters through the trees, and to avoid weekends and the middle of the day in July and August. An environmental interpretation centre at the entrance explains the volcanic activity, the plants and the animals of the area, and from there a path leads up the valley, passing a series of pools of different temperatures. The advice is to start with the lower pools and work your way upstream, ending with the big waterfall pool.

Practical points: bring swimwear, a towel and flip-flops, and know that the iron in the water can stain light-coloured swimsuits. Changing rooms and showers are provided, and a small fee is charged, which is higher than for many free attractions but includes the interpretation centre. Take care on wet rocks, which are slippery.

The site is easy to combine with other places in the area. The nearby town of Ribeira Grande has a pretty centre, and the road leads on to the Gorreana tea plantation, the oldest in Europe, and up to the crater lake of Lagoa do Fogo, one of the finest viewpoints on the island. On a rainy day, the warm pools and mist create a special mood. The site suits couples, families with older children and nature lovers who want a gentler, greener alternative to the busier springs.