The Azores have hydro-thermal resources, which have been known and exploited for centuries. There are various springs of natural carbonic water, waterfalls and iron water pools, which have been used since the sixteenth century. The highlight goes to the thermal baths Termas da Ferraria and the iron water pools in Furnas, on the island of São Miguel, and Termas do Carapacho on the island of Graciosa.