Grüner See

For part of each year the Grüner See in Styria hides a meadow under water. In spring, meltwater from the karst peaks of the Hochschwab range pours into a shallow basin and floods the surrounding grass, footpaths, benches and even a small bridge, which then lie visible beneath water so clear that underwater visibility can reach 50 metres.

The lake lies at about 770 metres near the hamlet of Oberort in the municipality of Tragöß-Sankt Katharein, ringed by forest and three mountains: Pribitz, Meßnerin and Trenchtling (Hochturm), the last rising to 2,081 metres. It exists because a prehistoric rockfall from the south flank of the Meßnerin dammed the valley. The water stays cold, at roughly 5–7 °C, and its level follows the seasons: in winter the lake can be only one or two metres deep, it reaches its peak of around 10–12 metres in late spring and early summer, and by autumn it largely drains away underground, leaving the meadows dry again.

The emerald colour comes from deep, pure water absorbing red light, helped by fine suspended limestone particles and a pale stone floor that reflects light back up. Sheltered from wind in its hollow, the surface rarely ripples, so the bottom can be seen even at a shallow angle. Snails, water fleas, small crustaceans and trout live in the lake, though plants are sparse on its rocky bed.

The lake became famous in 2014, when photographs of its underwater meadows spread online and Austrian television viewers voted it the country's most beautiful place. The resulting crowds stirred up sediment, and since 1 January 2016 diving, swimming and boating have been banned to protect the water.

Getting there

The lake is in the Tragöß valley, roughly 20 km northwest of Bruck an der Mur, the nearest town, which lies on Austria's Southern Railway. The nearest airport is Graz Airport (GRZ), about 68 km away.