On the bank of Switzerland’s Lake Zug, there is a door.. that takes you down.. to an underwater observatory where you can’t see much.
However, if you look at the doorway straight on, it’s reminiscent of the ‘door to the real world’ from the movie, The Truman Show, starring Jim Carrey as Truman Burbank. For those who don’t know about the film, you can see the reference here.
According to the photographer (who shared the photo on Reddit), the underwater observatory is small, it’s the size of an elevator. It’s about 20-30 steps down and there is a window which others suggest you don’t usually see much from aside from maybe some fish.