Caldeiras Das Furnas (Thermal Pools)

In the middle of the village of Furnas, on the eastern side of São Miguel, the ground steams, hisses and bubbles. This is the Caldeiras das Furnas, a field of fumaroles and boiling springs that shows the island's volcanic heart more directly than almost anywhere else in the Azores. The name means the cauldrons, and the description is accurate: pools of muddy, grey and rust-coloured water boil and spit, vents release clouds of steam, and the smell of sulphur hangs over everything. These are not bathing pools. The water is far too hot, and the ground around it is fragile and hot, so visitors watch from boardwalks and designated paths.

Furnas sits in the caldera of a large volcano that has been dormant, though not extinct, for centuries, and the heat that rises beneath it feeds the hot springs, mud pots and gas vents scattered through the village. The water carries dissolved iron, sulphur and other minerals, which stain rocks and soil in shades of orange, yellow and brown. In a few spots, springs of cold, naturally fizzy, iron-rich water emerge, and you can taste them from small fountains. The taste is sharp and metallic, and not to everyone's liking. Local people have long valued this water for its supposed health benefits.

The Caldeiras are also the centre of a famous food tradition. Cozido das Furnas, a stew of beef, pork, chicken, sausage, cabbage, potatoes, yams and other vegetables, is cooked by burying a sealed pot in the hot ground for about six hours. The heat of the soil does the cooking, and the stew emerges tender and slightly earthy in flavour. In the morning, you can see staff from local restaurants lowering their pots into holes marked with numbers, and around midday, they pull them out in clouds of steam. The area where this takes place is close to the Caldeiras, and watching it is one of the sights of the village. Many restaurants in Furnas serve the dish, and you usually need to book ahead.

For an actual soak, the thermal pools in the Terra Nostra Park and the Poça da Dona Beija are a short walk away, with warm, iron-rich water in garden settings. The lake, Lagoa das Furnas, is a short drive or walk, with a path around its shore and a small chapel on its edge, and the scenic viewpoints above the valley are well worth a stop.

Take care near the vents. Stay on the paths, keep children close and follow any signs, since the ground can be very hot and the gas can irritate the eyes and throat. Wear shoes that can cope with mud and bring a light layer, as the weather is changeable. Entry is generally free, and the area is open during daylight hours. The Caldeiras suit anyone curious about volcanoes and traditional food, and they make a good starting point for a day in Furnas.