Bat cave.
The guided tour lasts around an hour and you are able to walk 1 kilometer into the cavern. The cave is an important hibernation location for at least 3 species of bats and so it cannot be visited during the winter period. During the winter the cave is also flooded with many waterfalls as the winter rains seep down into the limestone rock.
A consequence of the constantly running and dripping water is the presence of a wide variety of calcareous formations. From finger sized starter stalactites to giant stalagmite pillars. Over the millennia the shape of cavern is incrementally evolving, the rock is truly living. We took the 11am tour. Afterwards we struggled to find somewhere for lunch and ended up back at the restaurant at the cave. We were pleasantly surprised at the quality of the cooking.