Terme di Saturnia, Natural hot spring in Manciano, Italy.

Terme di Saturnia is a natural hot spring in Saturnia, a village within the municipality of Manciano in Tuscany. The warm water flows over limestone terraces and forms several shallow pools where sulfur vapors rise above the surface.

The site was used for thermal holidays since Etruscan-Roman times, and Roman patricians stopped there along the Via Clodia. In 1188 a bull of Pope Clement III to the canons of Sovana mentions the "Bagno di Saturnia" as property of the Sovana diocese, with shelters for travellers and a mill downstream fed by the spring. In 1216 the property passed to the Aldobrandeschi counts; after a period of neglect the baths were restored in 1572 within a land-reclamation project.

The name comes from a legend that the god Saturn, angry at human warfare, threw a lightning bolt that opened a crater from which the hot sulphurous spring rose; the water calmed men and brought a golden age. The spring pool lies inside the resort, while the free Cascate del Mulino are fed downstream at a lower temperature.

The resort and the Cascate del Mulino are open all year round. By car, take the SS 74 Maremmana, then the SP 159 near Manciano and the SP 10 della Castagneta near Montemerano. The spring water reaches the falls at a lower temperature than the 37.5 °C of the source.

The water maintains a steady temperature of 37.5 degrees Celsius all year round, even during winter. The high concentration of sulfur and thermal plankton makes the water slightly cloudy and gives it a distinctive smell.