Slovenia lies in the karst area, where beautiful underground shapes are created due to permeable rocks and subsurface water flow.
Today, just over 9,000 caves have been discovered in this small area, and many are still hidden from human eyes. A unique ecosystem is created in the caves, as in addition, numerous stalactite forms, lakes, rivers, and many animals can be found in them. With 85 representatives of animal species, Postojna Cave is the most biodiversity-rich cave in the world, and it also boasts the first single-track cave railway in the world. The beautiful Vilenica Cave, where the fairies are said to live, is one of the oldest tourist caves in the world, as guides have been hosting tourists here since 1633. An exceptional natural heritage site is the UNESCO-listed Škocjan Caves, which hide the deepest underground canyon in the world.