This lake in Styria, at the foot of the mountain Hochschwab, is in fact, the park, which in late spring and the first half of summer goes under water. In May, when the meltwater comes down from the glaciers and peaks of mountains, the lake becomes full, the paths and trees are under water, and everything becomes surreal. If you have ever imagined how a submarine park in Atlantis would look like, then Green Lake is quite comparable with an underwater civilization.