*This post was previously live on my older/erstwhile site TheWingedFork.
A Lake Under A Lake Under A Mountain!
Seegrotte’s underground Blue Lake, and the tale to go with it. Gluck Auf!
So as I was saying last week, it turned out to be a bargain. For around 49 Euros each we got to see Heiligenkreuz Abbey, Karmel Mayerling, and Seegrotte Hinterbrühl, and didn’t have to shell out anything for transport or entrances.
If you missed last week’s blog, my sis and I were boarded at the Austria Trend in Vienna for a week and were running out of time on our last day in Vienna. So we didn’t want to waste time waiting for connecting buses from Wien Oper to Baden bei Wien, and then from Baden bei Wien to Karmel Mayerling.
By the way, if you’re looking for hotels to stay at, my friend Anca has some great suggestions for where to stay in Vienna.
While looking for day trips from Vienna, someone told us about this half day seat in coach trip that would take us there and be economical as well.
So we joined this trip group to see Karmel Mayerling and got to see Heiligenkreuz Abbey and Hinterbrühl Seegrotte as well. So last week I covered my sister’s crazy voices after seeing Mayerling Chapel. This week I continue about Seegrotte, Austria.


The tour of Seegrotte Hinterbrühl
The Seegrotte tour began with a walk of 450 feet through a narrow tunnel into the heart of the Hinterbrühl mountain.
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We reach a large chamber that in the upper level where we have to go down steep slides to the lower level. The guide made us go through in groups of four. Well, except for him. He just whizzed down on his own.
We almost expected not to stop at the bottom and fly over the end, but surprisingly all of us stopped just short of flying over the end. Some really good mechanics at work, though I haven’t gotten around to opening the textbooks yet.
At the lower level, we saw a number of artefacts and objects that were used in the gypsum mine when it was active from 1848 to 1912.
We also learnt about how an underground blasting operation that went off beam caused the mine to flood with 20 million litres of water, creating Europe’s largest subterranean lake.
The mine stayed closed till some cave explorers found it in 1930, post which it was opened as a museum to the public.


Gypsum Mine used as Airplane Factory
However, during the Second World War, the mine was taken over by Hitler’s army and used as an airplane factory. One of the world’s first fighter jets, the “Heinkel HE 162 Salamander” was built here. It was supposedly a secret weapon of the German Luftwaffe, but thankfully was never used.

As we travel further into the mine, we see a crystal clear lake called the Blue Lake. It’s about 3 meters deep and has a surface area of 300 square meters, with a water temperature of about 8 degrees Celsius.
By the way, one fascinating bit about the entire Seegrotte mine is that it is permanently 9 degrees Celsius down there, come rain or snow. Need to research about the how bit.
One more level down, and there is a Saint Barbaramuseum or a Barbara Kapelle that was constructed in 1864 in memory of all the miners who have lost their lives.
Saint Barabara is the patron saint of miners. Masses were held in this chapel every year till it couldn’t hold enough people anymore.
The two letters G and A on the altar read “Gluck Auf’ meaning ‘Good luck’! We also passed by a number of niche tombs in the walls for the miners.

We also saw a horse stable and a museum with artefacts from mining and from the airplane factory. The horses here supposedly never saw daylight again after reaching the mine.
They also lost their eyesight over time, since the mine did not have decent lighting in those days. Really crappy conditions. Where were the animal right activists in those days?
Ride on the Underground Big Lake
The last bit of the tour was a boat ride across another underwater lake called the Big Lake. The water in this lake would usually around 2 meters high, but is kept waist deep by pumping out over 50,000 to 60,000 litres of water every night. Hence, it has an average depth of 1.2 meters and a surface area of about 6,200 square meters.
I wanted to ask why they needed to pump out the water to attract tourists? Couldn’t they just let the mine fill up and use it as a great inland scuba destination? Maybe the mine owners never thought of that, eh?

Anyways, this lake was also used in the 1993 version of the movie ‘The Three Musketeers’. There’s a replica of the vintage-looking boat that was used in the movie too. So we start the 10 or 15-minute boat ride (on another modern-day boat), get a few good pictures, but my camera’s finding it difficult to adjust to the dark. So I rely on my sister for photographs.


Surprise on the Lake
But at one point in the ride, we are told that we’re exactly 20 meters (I think the guide said 20 meters) below the Blue Lake that we’d seen a while back. That was amazing!
Just the chance to tell people that you rode a boat on a lake that was under another lake under an Austrian mountain. That was the best part. Absolutely worth it!
I probably won’t go to Seegrotte again. Well, unless they turn it into a scuba tunnel for me. It may be a bit overrated, but for a one-time visit, it was something to remember and talk about. And blog about too! 😉
Information about Seegrotte, Vienna:
Grutschgasse 2a, 2371 Hinterbrühl, Austria
Mail: [email protected]
Phone: +43 (0) 664 26 24 454
Website: https://www.seegrotte.at/
Other Info And Things You Might Need
Other Posts to Read
- I lost my apple twice: Misadventures in a Kayak
- Hiking Tongariro
- Where to eat in Goa
- Weekend break to Northern Ireland
- Tung fort in Maharashtra


Wow this looks so cool & so interesting. I’ve never heard of it but I’d say it’s definitely worth a visit to see what it’s all about & that blue lake looks awesome!
Thanks Katie! We struggled a bit with the photos because of the shortage of light down there. But yes, it was definitely worth it to be able to tell someone that I went on a boat ride on a lake that was under another lake under a mountain. 🙂
I adore underground tours, aving taken similar tours in Naples and Prague in the last year. Seegrotte looks super interesting, it’s great to explore underground and understand how life used to be!
Yes, Underground tours are always awesome. I haven’t had the chance to do visit Naples and Prague yet. But they’re on my list.
And this lake in Austria too was a must to, at least once!
Awesome post on a place I never heard of! Although I have visited Vienna, I never went to Seegrotte. It’s looks really atmospheric and the fact that “The Three Musketeers” was filmed there ups its cool factor!
Thanks Suzanne! Yes, the fact that The Three Musketeers was filmed there definitely made it more interesting. But the fact that it was part of the World War was amazing too!
This is so cool! The underground reminds me of the salt mine tours in Poland. I would love to check this out!
Ah, all these underground mines do tend to be similar, don’t they? I found the salt mines in Berchtesgaden, Germany similar too, except for the structure! Maybe it’s the aura of the underground 😉
Wow what a great experience. It’s great to see that they’ve turned this into a museum/tourist attraction. I could never imagine having to work in a mine. Scares to begebus out of me.
Yes, it must have been dreadfully hard work for the miners. It’s really good that mines around the world have modernized, except for some countries.
Awesome. Floating on a underground lake, inside a mountain, thats underneath another lake – and in the beautiful Austrian countryside. Thanks for sharing this amazing experience and introducing it. We will have to do this when we visit Austria.
Thanks! And don’t forget they also claim that it’s Europe’s largest underground lake. You definitely have to visit!
I love underground tours and like someone already said in the comments, it reminds me a bit of the salt mine tour in Poland. It’s a little creepy to enter what’s basically a dark hole but I feel a bit more relaxed once I’m there.
Ah, it didn’t feel that creepy to me. But it was a pretty long walk here in the dimly lit in the tunnel of 450 feet.
Oh, so this is the one you’re talking about! Yes, it does look like the cave grotto in Neuschwanstein! I guess it’s a European thing? Ha! And wow, riding a boat down a lake under another in the Austian mountains?? Did I get that right? I can’t quite imagine it, but it sounds awesome!
Yes Sarah! It does look a lot like the one from Neuschwanstein in your blog. Maybe you could make your next trip there and compare. 🙂
This looks like a really awesome trip, rich in history and beauty. The underground Big Lake sounds so interesting. It must have been an otherworldly experience for you!
Yes Nadine! It was different. Learning about the history of the mines was the best part.
What an interesting attraction and that’s nice that you were able to squeeze in time to go to Seegrotte before you leave. I am a bit claustrophobic so I am not sure if that’ll be something I’d try myself. But if you’re in Vienna, might as well take advantage of the sights!! I need to check out that other post you were talking about!
Ah, that’s bad. But it’s quite airy once you get down there. And I hope you get the chance to read the Mayerling post. Writing about my sis and the coffin was fun! (Except when it was scary .)
Ah, that’s bad. But it’s quite airy once you get down there. And I hope you get the chance to read the Mayerling post. Writing about my sis and the coffin was fun! (Except when it was scary.)
Sounds like a cool experience (once) — maybe they will let you scuba next time 🙂
Ah, no. They’d have to actually stop pumping the water out for that, and change the type of museum. The visitor count and type would change too if they did that.
That boat ride looks very cool. I love following in really old history.
Thanks Alice. The boat ride was good. The only other underground boat ride I’ve been on was at the Cuevas Drach in Majorca, Spain, but that was hardly a 1 minute ride. This on the other hand was longer and filled with more stories.
This is really interesting! I love hearing about new places to visit, and I certainly have not heard of this one! Having a musuem inside a mountain / underground is something I haven’t come across before. I did once find christmas scenes inside a cave in the UK but that’s about as close as I can get! 😉
Thanks Justine! I have seen other mine museums, but they haven’t been under a mountain. So this was a good kind of different.
What a fun tour! I love boat rides, yours is definitely unique that you were in a mountain riding a boat on a lake.
Thanks Katie! Yes, it was exceptional in that.
I enjoy reading about locations that are new to me. Thank you for sharing your adventure.
Thanks Jamie! Glad you enjoyed reading the blog.
Wow! this sounds super fun! I’ve never heard about it, so I’m so glad I got to read your blog and learn about. Great job:)
Thanks Cass. It was fun! Glad you enjoyed reading about it!
This sounds so cool – interesting combo of caves plus WWII history! I’m also really curious how it always stays the same temp down there, if you ever find out, please let me know.
Ah, I’ve tried researching a bit, but couldn’t find the exact explanation. Will let you know when I find out.
I like how this was actually a bargain trip and yet it ended up so much more interesting than just taking the public trains.
Thank you for sharing & happy continued travels!
C
Thanks Carola! Yes, it was more than we expected. And getting into the additional places was a bonus. 🙂
Awesome post – so informative too, I had no idea Europe had such a gigantic underground lake. Also that mine looks freaky, I’m usually pretty fearless but I have a weird thing about tunnels :\
Thanks Serena! Yeah, it was a pretty big lake, but only upto 25 feet deep I think. The mine isn’t that scary when you compare it to catacombs, is it?