It rises in the Lucanian Apennines in Basilicata (where it is known as the Mercure) and drains into the Tyrrhenian Sea near Scalea in Calabria.

Its source is near the Serra del Prete mountain in the Pollino massif, at an altitude of 2,181 meters.

It has a drainage basin of 594 square kilometres (229 sq mi).

[1] Pliny, Ptolemy and Strabo all describe the river and note that it was the boundary between Lucania and Bruttium in classical antiquity.

[2] The archaeological site of the ancient Greek colony Laüs is located close to the river's mouth in the frazione Marcellina of the comune Santa Maria del Cedro.