Grüner See
Steiermark
Grüner See, located in the village of Tragöß in Styria, Austria, is a remarkable natural lake renowned for its vibrant emerald-green water. Nestled at the foot of the Hochschwab Mountains, it is surrounded by forests and peaks such as Pribitz, Meßnerin, and Trenchtling. The lake's water originates from snowmelt on the karst mountains, resulting in remarkably clear and cold water with temperatures around 6–7 °C. During winter, the lake is shallow, approximately 1 to 2 meters deep, and the area serves as a county park with meadows and walking paths. In spring, as snow melts, the basin fills with water, reaching depths up to 12 meters by mid-May to June, creating a unique underwater landscape where submerged meadows, trails, trees, and even a bridge and bench can be observed by divers. Due to its fragile ecosystem, all watersport activities including diving and swimming have been prohibited since January 2016 to protect the lake's clarity and environment. The lake supports diverse fauna such as trout and various aquatic invertebrates, though its rocky bottom limits abundant plant life. Grüner See is celebrated for its extraordinary underwater visibility, reaching up to 50 meters, and its striking emerald hues caused by the absorption and reflection of light through pure water and suspended fine rock particles. This natural phenomenon makes Grüner See a captivating destination for nature lovers and photographers alike.
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Tip: The best time to visit Grüner See is from mid-May to June when the lake is at its deepest and most visually stunning. Visitors should note that since January 2016, all watersports including swimming and diving are prohibited to preserve the lake’s delicate ecosystem. It is advisable to check local conditions before visiting, especially as the lake can nearly dry out in autumn. Purchasing tickets or reservations are generally not required as the area is a public park, but visitors should respect the environmental regulations in place.
Interesting facts
- •The lake’s water can reach a visibility of up to 50 meters, making it exceptionally clear.
- •In mid-May to June, submerged features like a bench, a bridge, trails, and trees become visible underwater.
- •The lake’s green color is due to pure water absorbing red light and reflecting blue-green wavelengths, enhanced by fine suspended rock particles.
- •Grüner See was voted the most beautiful place in Austria in 2014 by viewers and a jury on an ORF TV show.
- •A viral 2014 Facebook post by Ashton Kutcher significantly increased international awareness of the lake.
- •Since 2016, all watersports including diving and swimming have been banned to protect the sensitive ecosystem.
History
Grüner See's basin was formed by a prehistoric landslide from the Meßnerin mountain, creating a natural dam.
The lake's water level fluctuates dramatically with the seasons, filling during spring snowmelt and nearly drying out in autumn.
In recent history, the lake gained international attention in 2014 through social media and was voted Austria's most beautiful place in a national TV show.
Due to rising tourist numbers and ecological concerns, authorities prohibited all water-based recreational activities starting January 2016 to protect the lake's fragile environment.
Notably, in April 2025, the lake completely dried out, a rare event attributed to insufficient winter precipitation over the previous decades.
Place Guide
Surrounding Mountains
The lake is encircled by three prominent peaks: Pribitz (1,579 m), Meßnerin (1,835 m), and Trenchtling (2,081 m), which form part of the Hochschwab Mountains and create a sheltered basin for the lake.
Underwater Meadows and Features
During the lake’s peak depth in late spring, underwater meadows, a submerged bench, a small bridge, and trails become visible beneath the crystal-clear water, offering a unique diving and viewing experience.
County Park and Trails
In winter and autumn when water levels are low, the lake basin serves as a park with walking trails and benches, allowing visitors to enjoy the alpine scenery on land.
