The „Hochschwab“ is probably the most impressive massif on the eastern edge of the Alps. At the foot of the Hochschwab to its south you find one of the most stunning and imposing landscapes of the area, the “Tragößerland”. Surrounded by the steep limestone walls of the “Pribitz” and the “Trenchtling” reaching to the sky, the “Grüner See” is an especially charming lake, a karst lake clear as chrystal and of a colour that resembles tropic oceans. Millions of years ago there was indeed an ocean there, the Tethys, the primal ocean. The film provides an insight into the evolutionary history of the mountains and valleys around the “Grüner See” and follows some of the animal species living there throughout the seasons.