Norra Lunsen1 is a nature reserve right next to the Swedish city, Uppsala. A while ago they decided to restore the original, marsh state of the area. You mostly walk on wooden planks and the green "meadow" below you is not grass; it's pitch black water covered in duckweed. The creaking of the half-dead trees, the black water and the silence are all adding up to a pretty much haunted feeling. If you happen to be close to it, visit it.
(Oh, by the way: this entry was written by Peter Molnar, and originally posted on petermolnar dot net.)