[1] The Santu rises in the commune of Santo-Pietro-di-Tenda to the southeast of the 421 metres (1,381 ft) Monte Genova.

It flows in a generally northeast direction to enter the sea in the Golfe de Saint-Florent to the south of the Torra di Mortella.

It contains meadows of salt-tolerant rushes, with large populations of samphire that turn red in the fall.

Birds include mallard (Anas platyrhynchos), little grebe (Tachybaptus ruficollis) and common moorhen (Gallinula chloropus).

[3] The following streams (ruisseaux) are tributaries of the Santu, ordered by length, and sub-tributaries:[1]