The Seegrotte was created in 1912 after a blast in what was then the Hinterbrühl gypsum mine. More than 20 million liters of water flowed into the passages and tunnels, the result of this massive flood is the largest underground lake in Europe.

Twenty years after the blast, the Seegrotte was made accessible to visitors for the first time and opened as a  show mine  . In the course of the Second World War, the lake was completely pumped out and drained to produce one of the world's first jet fighters - the Heinkel HE 162 "Salamander". Parts of the jet fighter can still be visited today. After the facility was completely destroyed by heavy bombs in 1945, the Seegrotte could only be visited again from 1948


The blue lake in the Hinterbrühl

The highlight of the Seegrotte today is the "Big Lake", also known as the "blue lake": 60 meters below the surface of the earth, it is the  largest underground lake in Europe . The lake has an inflow from seven underground springs, but no natural outflow. In order to be able to maintain the average depth of 1.20 meters, between 50 and 60 thousand liters of water are pumped away every evening.

Getting Here From Vienna:  From Vienna take the Underground Metro to Vienna’s Meidling Train Station on the Southside of town and take a local train right to Mödling.  Trains leave about 10 times an hour and the ride is only 15 minutes south of Vienna.  At the Mödling Train Station, you take either Bus 364 or 365 right to the entrance

Tip: It is around 9 degrees in the grotto in both summer and winter, so don't forget a warm jacket!

Grutschgasse 2a in 2371 Hinterbrühl

For more info and booking: 



Explore the place

The City Maps