The Calore (108 km), Irpino to distinguish it from the homonym river of Lucania, finds its sources on the Accellica Mountain in the Picentini chain, in the cities of Montella and Cassano Irpino.

It is the second river of Southern Italy due to its volume of water. The Sele (64 km) rises on the north-eastern part of the Monte Plafagone (foothill of the Cervialto), at an altitude of 420 meters, in the district of Caposele.

The ancient Aufidus, who, according to the legend, was surpassed by the elephants of Hannibal thanks to the bridge built close the actual Lioni, finds its source in the wood of Piano dell’Angelo, at 715 meters of altitude, close to Torella dei Lombardi.

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.

It is defined as an "area of scientific interest of the WWF".

After the Unification of Italy, taking advantage of thick wood of beeches, the brigands found there a safe shelter. At an altitude of 1050 meters, the highland of the Laceno in the district of Bagnoli Irpino extends between the Monti Picentini, at the foot of the Cervialto, and surrounded by other summits of the chain.