Gruner See, a vanishing green lake during snowmelt season

Located at the foot of the snow-capped Hochschwab Mountains, Grüner See is one of the most breathtaking natural wonders in Styria (Steiermark), Austria. This vanishing green lake is famous for its seasonal transformations, offering a surreal underwater landscape unlike any other on Earth. During spring, as the snow melts, the lake basin fills with ice-cold, emerald-green water, submerging meadows, trees, park benches, and walking paths, creating an enchanting underwater paradise.

Location of Grüner See in Styria, Austria

This seasonal green lake with its crystal-clear waters is located in the small village of Tragöß. A village that is part of the municipality of Tragöß Sankt Katharein, in the federal state of Styria (Steiermark in German), Oberort district, Austria. Gruner See, or Gruner Lake, lies at the southern foot of the Hochschwab Mountains, a 400-km-long mountain range that is part of the Alps.

Gruner See is a seasonal green lake

The Stunning Natural Beauty of Gruner See Austria

Gruner See, situated at an elevation of 776 meters above sea level, is a stunning natural tourist destination in Austria. Surrounded by a range of three towering mountains exceeding 1,500 meters in height—Pribitz, Trenchtling, and Meßnerin—this seasonal lake is an integral part of the enchanting Hochschwab Mountains. The natural beauty around Gruner See is further enhanced by lush pine forests, alpine meadows, and beautiful wildflowers. 

Underwater garden of Gruner See in Austria

Why Grüner See Has Crystal-Clear Emerald Water

Gruner See receives no inflow from any rivers. The lake’s water comes solely from melting mountain snow, which is why it is so clean and clear, however, the water temperature is extremely cold, ranging from about 6–8°C. The name Gruner See, meaning “Green Lake,” derives from the emerald-like color of its water. The exact size of this Austrian lake cannot be determined, as its dimensions constantly fluctuate with the seasons. Gruner See can be considered a seasonal lake. It is truly unique because it transforms into a large, beautiful lake at certain times—specifically when it receives an abundant water supply—yet at other times, this stunning green lake simply vanishes.

Flora and Fauna of Gruner See Seasonal Lake

From late fall through winter, Gruner See takes the form of a natural pond with clear water, only about 1 to 2 meters deep. In fact, the pond sometimes disappears entirely. In the spring, as temperatures rise and the snow begins to melt, Gruner See starts to fill with water, and its size—which was originally just a small pond—gradually transforms into a small lake with crystal-clear water. This green lake in Austria is also home to various aquatic fauna, such as small crabs, snails, water fleas, and various species of trout. However, because the lake’s bottom consists of rock, Gruner See has very little aquatic flora.

The Seasonal Transformation of Gruner See (Green Lake)

In April, Gruner See begins to fill with melting snow. The limestone dust contained in the melting snow gives the lake’s water a distinct blue-green hue. The lake’s water level depends on the amount of snow that fell during the previous winter. During the summer, the depth of this emerald-green lake can reach 8.5 to 11 meters. When the snow hasn’t fully melted yet, Gruner See looks like a small natural pond, surrounded by a beautiful natural park with lush green trees. There are also benches in the area for resting. It is truly a beautiful and romantic park! As the temperature rises and the snow melts, the lake gradually expands. The surrounding park, walking paths, small bridges, and benches will disappear, submerged into the lake.

Underwater park at Grüner See with submerged benches and trees

The Magical Underwater Garden of Grüner See

During the summer, Gruner See transforms into a true seasonal green lake. From mid-May through June, the lake reaches its maximum size. Its emerald-green waters create a breathtakingly beautiful scene. And even more astonishing is the view at the bottom of the lake. The submerged garden transforms into a stunning underwater garden in Austria. Anyone swimming in Gruner See is sure to be captivated by the extraordinary beauty of this underwater paradise, featuring green grass, tree trunks, and even wooden benches, walking paths, and small bridges.

Why Water Sports Are Banned at Grüner See Austria

Since January 1, 2019, local tourism authorities have banned all water sports activities on Gruner See, including swimming, diving, and boating. This decision was made to prevent damage to the environment of this beautiful lake. There are concerns that water sports on this green lake could stir up sediment at the bottom, potentially damaging its iconic emerald green color. Of course, with this ban in place, tourists can no longer dive and enjoy the enchanting underwater garden of Gruner See.

As the seasons change and the water slowly recedes, the magic of this vanishing green lake fades, revealing the lush green meadow that was once hidden beneath its surface. It is this natural cycle that makes Gruner See so special, with its ever-changing landscape, marked by its shimmering green water and fleeting beauty. Though brief, the transformation of this emerald-green lake is a unique attraction that captivates tourists from all over the world.

(Latest update in 2026)
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