The caves, gorges, underground halls, underground rivers and lakes invite you to peek into the hidden and rarely seen spaces in the interior of the country. In the area of Lika, in a town called Perušić a cave complex Grabovača has been renovated, and close by it one can find a couple of dozen of other unexplored caves.
Caves called Cerovačke pećine are located in the southern part of Velebit Nature Park, four miles southwest of Gračac. They are among the best known and most important speleological objects in Croatia. The complex consists of three caves (Lower, Middle and Upper) with a total of 4 km of explored channels. For tourist visit the first 700 m of the Lower and Upper Caves have been opened.
Lukina jama in the Northern Velebit National Park, 1431 m deep, is the deepest cave in Croatia and today the fourteenth deepest cave in the world.