Externsteine

Huge rock formations in the middle of a forest and next to a shallow sea. Only accessible by car via a parking lot. This spot is super weird. It look awesome and you want to train, but then you look at it from up close and have no idea what to do. Not only are the guards watching out for people climbing the rocks, but they are also hard to make use of. The bottom parts are either surrounded by bushes or just unusable big walls.

Also filming seems to be prohibited if its for "offical videos". No idea what that means, but they do not seem to care about GoPros and cellphones, only huge cameras and drones seem to piss them off

I was not able to see how deep the sea is, but I would not recommend jumping from the rocks. However it is a great place to swim at. And if its night you can sneak up the rocks and sleep there in a hot summer night