Lake Cerknica

Lake Cerknica (Cerkniško jezero) is an intermittent karst lake. At full level it covers about 26 square kilometres and is then Slovenia's largest lake; for roughly eight months a year it covers about 20 square kilometres. The water drains away through swallow holes (ponors), so the same area serves for paddling, fishing, walking or mowing depending on the season. The lake lies on a karst polje between the Javorniki hills, the Bloke plateau and Mount Slivnica. It is a Ramsar wetland and a Natura 2000 site, chiefly because of its endangered bird species.

More than 300 bird species, 45 mammal species and 125 butterfly species have been recorded in the area. The naturalist Johann Weikhard von Valvasor studied the lake, and his work is regarded as a forerunner of karstology. Check the current water level before you travel, as it decides whether you find a lake or a meadow. Binoculars are worth bringing for birdwatching.