Visitor Center (by Lake Cerknica)

Lake Cerknica is the largest intermittent lake in Slovenia, and one of the largest of its kind in Europe, and it is among the most unusual natural features in the country. It lies in a broad karst basin in the Notranjska region, south-west of Ljubljana, and it fills and empties according to the seasons. After autumn and spring rains the water wells up from underground channels and spreads across the plain, forming a shallow lake that covers many square kilometres, and in dry summers the water drains away through sinkholes, leaving meadows, fields and a muddy bed. The mechanism has fascinated scientists for centuries, and the seventeenth-century Carniolan polymath Janez Vajkard Valvasor wrote about it in his famous description of the duchy.

The visitor centre is the best place to begin, because it explains what is happening. Exhibits, models and displays show how water flows through the underground network of caves and channels, why the lake rises and falls, and how people have adapted to its rhythm over the generations. Fishermen, hunters, farmers and boatmen all used the lake in different seasons, and the traditional tools and methods are part of the story. The centre also describes the plants and animals of the area: the lake and its surrounding wetlands are among the best places in Slovenia to see birds, with herons, ducks, waders and many migrating species passing through.

Staff at the centre can advise on routes and activities that depend on the water level. When the lake is full, boat trips and canoeing are possible, and fishing is allowed under licence. When it is dry, walkers and cyclists can follow paths around the edge and across the bed, and the flat terrain makes for easy riding. In severe winters, the frozen surface has been used for ice skating, though this depends on conditions and safety. The surrounding hills and forests, with their caves and sinkholes, offer more walks, and the whole area lies within the Notranjska Regional Park.

The visit works well as a half-day, with the exhibition taking an hour or so and the rest of the time given to walking or cycling around the shore. Because the landscape changes completely with the season, it can be worth returning at different times of year. The nearby Rakov Škocjan valley and Postojna Cave make good companions, so Lake Cerknica fits into a day of karst exploration. Opening hours and activities vary by season and water level, so it is wise to check before travelling.