Grüner See (Green Lake) is a lake in Styria, Austria. In the winter you’ll find crisp, tranquil grasslands and lake that is only about 3 to 6 feet deep.  However, during the spring, when the temperature rises and the snow melts, the basin of land below the mountains fills with water. The lake reaches its maximum depth of around 40 feet from mid-May to June and is claimed to look the most beautiful at this time.