Skocjan Caves, Slovenia

Slovenia-3, originally uploaded by Abhishek's Received Postcards.

Škocjan Caves is a system of limestone caves in the Kras (Karst) region in southwestern Slovenia, containing collapsed dolines, about five kilometres of underground passages, caves more than 200 metres deep and many waterfalls. This is one of the best-known sites in the world for the study of karstic (limestone) phenomena.