Skocjan Caves - Matavun, Slovenia

These caves are referred to as being the “Underground Grand Canyon,” as it is among the largest subterranean chambers in the world. The largest cave is “Martel’s Chamber,” formed by the underground flow of the Reka River. The limestone caves were a home to humans for as far back as 10,000 years ago. It is now home to a number of species of bat, unique bio-organisms and fish that have never seen the light of day.