The Azish Tau Ridge in the Western Caucasus is known for its karst caves, which permeate a group of mountains, creating a complex network of underground routes. Some of them, such as the Great Azishskaya Cave, were first studied and explored many years ago and are nowadays equipped for tourist visits. The majority of these caves however, will only ever be documented and described by scientists and researchers – not tourists. RTG TV host Denis Golovko went along with professional speleologists to help study the underground pathways. Prehistoric animal bones and darkness-loving bats waited for him in the Earth’s depths, where he learned how to explore sunken caves using scuba equipment.