The Pertosa-Auletta Caves, 263 metres below sea level, are renowned throughout Italy. It is a complex of 3,000 metres of karst caves in the bowels of the Alburni Mountains, 1,200 of which can be visited. It can be accessed by a boat pulled by a steel cable. Grotte dell’Angelo, as they are called, are crossed by the Negro river and to reach the beginning of the underground route, you have to navigate a section of it. The river also gives life to the large waterfall you will come across along the way.