Speaking of caves, I was actually going to use that as a comparison of sorts, myself. I went into a very large and long cave in Venezuela many years ago(about 6 miles long and perhaps an average of 75-100ft diameter. The tour guides turned off their lanterns for a few seconds when we were deep in the cave, and it was indeed very disorienting....absolutely pitch black, and quiet to the point of near panic! You knew you were holding your hand an inch in front of your face, but couldn't see it or make it out at all.
Guachero Cave Venezuela.
