Dolina is a word of Slovenian origin and simply means valley. Given that the interest in the karst phenomena developed from the Slovenian territories, international terminology has designed that term to define more precisely a karst valley, which is a typical depression of the land molded into various shapes by karst phenomena. A dolina (sinkhole) is a closed basin that would fill with water giving rise to a pond if the walls and floor were waterproof, however, usually the water is absorbed through underground tunnels. Formed by the erosive action of rainwater, the sinkhole has an elliptical form and measures 250-300 m in diameter and is about 20 m deep.