Slovakia has over 2400 caves, of which only over 400 have been explored so far.

An excerpt from the article 37 facts about Slovakia

Five of them have been included on the UNESCO World Heritage List. These are: Dobšinska Ice Cave in Slovak Paradise, Domica Cave - Slovak Karst, Gombasek Cave - Slovak Karst, Jasovska Cave - Slovak Karst and Ochtyńska Aragonite Cave - Slovak Karst. There are 30 caves available to visitors. Most of them have stalagmites and stalactites.