A friend of mine worked one summer as a counselor at a boy scout camp in the southwest. I'm not sure exactly what the premise of the camp was, but I know they spent their time trying to live as 19th cenury miners. He doesn't exactly believe in ghosts, but he admitted that a lot of stuff happened that he could not explain.

He remembered hiking in the woods and hearing someone walking behind him, but finding no-one there. He said he thought it was his own footsteps echoing until he realized that the other footsteps were not uniformly out of synch with his (echoes would have lagged behind his, but these changed speed, stumbled when he did not, and did not stumble when he did). He also heard footsteps and voices when he was exploring the reconstruced mines, at times when he knew there was nobody else in the mine and when there was no possible source of echoes.

He also told of footsteps at night in the cabins, things moving mysteriously, and loud noises when nothing had been dropped or broken. I don't think anyone ever saw anything but he admitted that it really gave them the creeps for most of the summer