The Sarthe (French pronunciation: [saʁt] ⓘ) is a 313.9-kilometre-long (195.0 mi) river in western France.

Its source is in the Orne department, near Moulins-la-Marche.

It flows generally southwest, through the following departments and towns: Its main tributaries are the Loir and the Huisne from the left, and the Vaige, the Erve and the Vègre from the right.

[1] The Sarthe has 20 weirs and locks.

[citation needed] The channel is well marked and navigation is straightforward, except for the risk of shoals in certain sections.