Skocjan Caves, Slovenia

Skocjan Caves is a spectacular cave system in southwest Slovenia with impressive stalactites, stalagmites, and other interesting rock formations, but what sets this cave apart from other caves is the underground Reka river and the largest discovered underground cavern in all of Europe (and one of the largest in the world). The cavern is of colossal proportions with a river running way below it — it seriously feels like you’ve been transported into Tolkien’s Lord of the Rings and you are about to witness the battle between Gandalf and the Balrog — the chamber is that huge. The cave is several million years old and, due to its exceptional significance, the Skocjan Caves have been a UNESCO protected site since 1986.

The caves have drawn people for far longer than they have drawn tourists. Archaeological research shows human occupation of the caves and the surrounding area stretching back more than 5,000 years — from prehistoric times right through to the present. To the ancient peoples the magnificent entrances and the dramatic disappearance of the Reka River into the earth held deep symbolic power, an opening to the underworld comparable to the realm of the dead in Homer’s epics.

That sense of the sacred is borne out by remarkable finds. In the nearby 50-metre abyss of Mušja Cave, archaeologists recovered over 600 Late Bronze Age metal artefacts, weapons and animal bones — offerings from sacrificial rites performed above the cave. Pilgrims came to this cult centre from as far away as present-day Italy, the Alps, the Pannonian Plain, the Balkans and Greece. It is also from this landscape that the very word ‘karst’ (Kras) entered the language of geology worldwide.

Deep in the subterranean waters lives the caves’ most extraordinary resident — the olm (Proteus anguinus), known affectionately as the ‘human fish’ for its pale, fleshy, pinkish skin. It is Europe’s only exclusively cave-dwelling vertebrate: blind, with degenerated eyes, entirely aquatic, and astonishingly long-lived — individuals may survive more than a hundred years and endure many years without food. First recorded in 1689 by the naturalist Valvasor, the olms were once washed out by heavy rains and believed by local people to be the offspring of a cave dragon.

To descend into these vast, echoing halls, with the Reka thundering far below and the mist rising through the dark, is to feel the true meaning of the underworld — ancient, sacred, and utterly humbling.