I've heard a couple myths about a devil-style entity - usually a dragon or something who's planning on swallowing a world at the end of days, or something, but I've never really put much stock in that kind of legend before. Guess that's more stuff to learn...
We have no way of knowing where the holes are, or where they go to? If we did we could probably figure out a way back... unless they close back up behind people, I guess...
if you die here do you die back there, too? Do you come back dead or do you stay here and just never go home, so no one ever knows what happened?