Rocca San Felice is a town and comune in the province of Avellino, Campania, southern Italy.

It counts no hamlets (frazioni) but some localities as Carmasciano, Fontana dell'Olmo, Palombaia, Santa Felicita, Serro del Bosco, Taverna Bruciata, Toriello and Valli.

It was named after the ancient Italic goddess Mefitis, venerated by the people of Hirpini, and counts some ruins of a sanctuary of the 7th century BC.

The little lake is formed by a pool of water, about 2 metres (7 ft) deep, that boils as a result of the gas emissions of the subsoil, consisting primarily of carbon dioxide and sulfuric acid.

Because of this poisonous emissions, the surrounding area is free of animals and vegetation.