UNDERGROUND

Despite substantial precipitation, the karst surface is dry, because rainwater percolates through the porous limestone rock and down into large underground cave systems. The unique phenomena of intermittent lakes and sinking streams are but a glimpse into the magical world of the karst underground world, which enchanted the antique writers, as well. In the karst underground, water has carved out a myriad of shafts, tunnels and caves to find its way towards the Adriatic Sea. All the while, water drops - laden with calcite and other minerals from the karst soil and rock - have been patiently sculpting stalagmites, stalactites, draperies and other fascinating forms in a variety of colours. For millions of years, these speleothems have been gracing several thousands of wondrous underground caves which are scattered around the karst terrain.

In the Italian part of the Karst, nearly 3,000 caves of various sizes and depths have been registered. If you want to see one of the largest underground chambers in the world (360,000 m3), then you should visit the cave Grotta Gigante, which lies close to the village of Borgo Grotta Gigante (Briščiki) in the municipality of Sgonico (Zgonik) near Trieste. The neighbouring Slovenia is even richer when it comes to the number of exceptional karst underground caves. The Vilenica Cave has the longest tradition of speleological tourism in Europe. With its 26 kilometres, the stunning Postojna Cave is the largest tourist cave in the world. Due to their exceptional significance, the Škocjan Caves were entered on UNESCO's List of World Heritage Sites.

Experienced speleologists or other professionals who would like to research karst underground caves can contact a number of speleological associations, which will help them to visit the lesser known, but no less fascinating underground caves.