Now you see it, now you don’t! Well perhaps not that quickly but regardless Europe’s largest periodic body of water, Lake Cerknica, is truly a magical natural phenomenon. Its disappearing waters baffled people for centuries until none other than the 17th-century local hero Johann Weikhard von Valvasor explained what was going on, namely that beneath the fields where the lake forms is a subterranean landscape of karst springs, caves and sink holes which funnel water away, or otherwise in heavy rains overflow causing the fields to flood, and, voila, the lake appears. The lake is usually at its largest in spring, whilst when dry it becomes a green meadow where cattle graze and sinkholes litter the surrounding fields. No matter what time of year, Lake Cerknica is an impressive sight and it also provides the venue for countless outdoor activities, from swimming and biking to cross-country skiing and ice skating when the lake freezes over during the winter.