posted on Mar, 20 2003 @ 10:12 PM
I have explored a good number of caves (there are over 400 known mapped caves in my county alone, and likely at least as many unmapped). In my case,
many die out at relatively shallow depths, but I have spent over 20 hours in caves before, up to a km deep.
Depending on your area, there can be very extensive and interconnected cave systems. I personally believe in some parts of the world, there are very
accessible caverns that could potentially be hospitable for groups/communities that wanted to stay away from those topside....