Gruner See, or Green Lake, is a lake located in Styria, Austria. It is famous for its clear, emerald-green water, which gets its color from the submerged greenery at the bottom of the lake. The water comes from the snowmelt that descends from the mountains that surround the lake. This means that the lake’s water level changes depending on the time of the year. It is the highest at the beginning of summer and the lowest in winter. In summer, benches, trails, footbridges, and even entire trees can be found under the water!