Years ago, when some of my friends went camping in upstate New York, two of the guys got lost in the woods at night while tripping their brains out (in addition to all the weed they'd smoked earlier). Imagine nothing but total darkness, the threat of wild animals, and all the while you're in that condition. I'm pretty sure that a friend that I stay in touch with was one of those involved, so I may get more details - because an experience like that you do not ever forget.