50 kilometers long, the Sabato flows in Irpinia area. It starts on the Colle Finestra del Monte Terminio, and close to Altavilla Irpina it marks for a while the border between the provinces of Avellino and Benevento, where it keeps its watercourse. It receives water from some torrents, of Vallone Barra and Fenestrelle (11 km), which passes through the city of Avellino.

The mud boils in the barren expanse which occupies part of the valley formed by the Miscano river near Montecalvo Irpino.