Postojna Caves (Slovenia)
One of which is I am part Slovenian and have been there But also because of the immense underground cave network that is visitor friendly. The caves have over 24 km of wandering passages underground and contain various cool cave features like stalactites and stalagmites. The caves formed via an underground river (Pivka) ~ 2 million years ago that slowly eroded away at the surrounding reactive limestone bedrock. Cave formations likes stalactites form very slowly (between 0.1 to 0.3 mm/year) by water percolating down from the ceiling and depositing calcite that was dissolved in the water. In the caves also lives a special creature, the Proteus or “human fish”. It is an amphibian with no eyes, no skin colour pigment, and can survive several years without food.
