Rocca San Felice

In a valley nearby there is a pool of water that boils: it is not hot, it is the gas rising from underground. Carbon dioxide and hydrogen sulphide come out, and so much of it that almost nothing grows around and no animal lives there. Birds flying over it fell down dead, and to the ancients this was a door of the underworld.

The Hirpini had put a sanctuary there, in the seventh century before Christ, for the goddess Mefitis, from whom they asked wealth and protection: her altar is now in Capodimonte. The pool is some forty metres across and less than two deep; the carbon dioxide that comes out of it, nine hundred tonnes a day, is the highest quantity measured anywhere in the world.