The Ombrone (Latin: Umbro) is a 160 km long river in Tuscany, central Italy. The Ombrone's source is at San Gusmè, near Castelnuovo Berardenga, on the south-eastern side of the Monti del Chianti. After a twisting route, it receives the waters of the tributaries Arbia, Merse and Orcia before reaching the plain near Istia d'Ombrone. It subsequently passes near the city of Grosseto, before flowing into the Tyrrhenian Sea.