Seegrotte Hinterbrühl
Niederösterreich
Seegrotte Hinterbrühl is a remarkable former gypsum mine located about 15 km south of Vienna in Lower Austria. Since 1932, it has served as a show mine and is famous for housing Europe's largest underground lake, spanning approximately 6,200 square meters. The lake is fed by seven springs and maintained by nightly water pumping to control its level. Visitors can explore a labyrinth of tunnels and galleries, culminating in a memorable boat ride on the subterranean lake. The site blends natural geological wonders with significant historical layers, including its use during World War II as a forced labor site for aircraft production under the code name "Languste." After extensive renovations from 2019 to 2022, the mine reopened, continuing its legacy as a popular tourist attraction. The combination of its vast underground waterscape, mining heritage, and poignant wartime history makes Seegrotte Hinterbrühl a unique cultural and natural landmark in Austria.
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Tip: The best time to visit is during spring to autumn when the weather complements the underground tour experience. It is advisable to book tickets in advance, especially during weekends and holidays, to avoid long waiting times. Discounts are often available for groups, children, and seniors. Wear comfortable, warm clothing as the underground temperature remains cool year-round. Guided tours provide insightful historical and geological context, enhancing the visit.
Interesting facts
- •Seegrotte Hinterbrühl contains Europe's largest underground lake with a surface area of about 6,200 m².
- •The underground lake has no natural outflow and is maintained by pumping 50–60 cubic meters of water nightly.
- •During World War II, the tunnels were used as a forced labor site for the Heinkel aircraft factory under the codename 'Languste'.
- •More than 20 million visitors have explored the Seegrotte since it opened as a show mine in 1932.
- •The underground lake is on average 1.2 meters deep and is fed by seven natural springs.
History
The gypsum deposits around Hinterbrühl were known since the 18th century, with mining beginning in 1848.
The mine expanded significantly by 1851, including plans for an underground railway.
In 1912, a massive water inflow flooded the mine, creating the vast underground lake and halting mining operations.
In 1918, the abandoned mine was purchased with the intention to develop it for leisure and education.
It opened as a show mine in 1932 with electric lighting and boat tours on the lake.
During World War II, the tunnels were repurposed for aircraft production using forced labor under the Nazi regime.
After the war, the site continued as a tourist attraction and underwent major renovations before reopening in 2022.
Place Guide
Underground Lake
The largest underground lake in Europe, covering 6,200 square meters, offering visitors a unique boat ride experience inside the mine's labyrinthine tunnels.
Mining Tunnels and Galleries19th century
A network of historic gypsum mining tunnels dating back to the 19th century, showcasing mining techniques and underground architecture, including brick-lined sections from the 1920s.
World War II Aircraft Factory Site1943-1945
Sections of the tunnels were converted during World War II to house forced laborers who produced aircraft components for the German Heinkel factories, protected from bombing raids.
Contact
Phone: 02236 26364
