Grüner See, a lake which is about 3 to 6 feet deep during winter, sits near Austria’s Hochschwab mountains. The forests surrounding the park are perfect for hiking and exploring. But every spring, the mountains’ ice melts and the lake rises to about 40 feet deep, covering much of the surrounding park’s forests.
Because of the plants at the lake floor, the waters appear blue-green (hence its name). Divers are treated to a bizarre experience — park benches, healthy trees and intact hiking trails turn the landscape into something like a surrealist painting.
Though the lake is only high for a few weeks, Grüner See is definitely one of the coolest diving spots (at least as far as lakes go) in the world.