Fervedouro do Sono is located between Fervedouro do Ceiça and Cachoeira do Formiga in Mateiros. This site contains a well of spring water. The water is slightly cool and features a clear blue colour. The well's design is sightly square and a wooden platform helps visitors to access the water without stepping on the vegetation that colours the green margin. There is no trail to the fountain and access is quite easy on foot. The boiler has capacity for six people at a time and visitors can enjoy meals and relax in a hammock at the nearby restaurant.