The Cerknica basin is home to Europe's largest intermittent lake, which can cover an area of 38km² and reach a depth of 10m, but empties out in dry periods. The winter waters of Mt Javornik and Mt Slivnica fill it via the countless cavities, reservoirs and channels of the karst subsoil. A geological curiosity, the lake also boasts a wealth of wildlife: amphibious botanical species, nesting areas for many species of birds, aquatic fauna with surprising resilience.