Grüner See, literally “Green Lake”, is a lake in Styria, Austria, near the town of Tragoss, located at the foot of the snow-capped Hochschwab mountains. During winter, the lake is only 1–2 meter deep and the surrounding area is used as a county park. It is a particular favourite site for hikers.
But as the temperature starts rising in spring, the ice and snow on the mountaintops begins to melt and runs down into the basin of land below. The lake swells up to engulf the entire area including the park.
The Grüner See is 100% pure meltwater and begins to fill up during the thaw in late April. The maximum water level (8.5 – 11 m) is usually achieved around mid-May, after which the water level drops off quickly.
When the maximum water level is reached the Grüner See is a paradise for divers and underwater photographers.
Starting July, the lake starts to recede and by winter, the lake is back to its original size and the park is returned once more to the hikers.
Until late autumn only a small part of the lake remains at the deepest point. Since the water travels through various layers of limestone it is crystal clear but also very cold (4 – 6 °C).
The lake gets its distinctive green colouring, and the name, from the grass and foliage beneath, and thanks to the fresh snowmelt, the ice-cold water is crystal clear clear. The temperature of the lake is rather cold at 4 to 8 °C, yet it’s popular among divers who can observe the green meadows in the edge zone of the lake particularly in June when the water is at its highest. The alpine grasses and flowers of the meadow are visible in full bloom under the water. One can even see benches, a bridge and walking trails.