Slide 31 of 31: Surrounded by the Zillertal Alps and the Reichenspitz mountain range, the stunning Durlassboden Basin stretches between the Austrian states of Tyrol and Salzburg. The high-altitude reservoir (4,593ft/1,400m) is usually a hive of activity with hikers and cyclists doing the circuit around the water (there are cozy mountain restaurants to refresh along the way) or venturing further up in to the mountains. The lake is a lovely spot for swimming and watersports too, and lays claim to having the highest sail and surf school in Austria.