One of the gems of Slovakia, Domica Cave is famous for the underground river Styx, where tourists can cruise on small boats on guided tours. Most impressive are stalagmites and stalactites as well as the fact that the cave has been inhabited back in the Paleolithic period. Domica Cave was discovered in 1926 as part of the research of a large number of small caves, (712 of them) that form a large cave system. Archeological finds were discovered after that. The site is on the list of UNESCO World Heritage.