>>2853257My parents did spelunking in college and I've heard enough stories about bottomless pits and ceilings so low to the ground that you have to exhale to progress forward that I am uninterested in serious caving. I've been to Mammoth Cave, however, and it was great.
There's one fairly large room we stopped at on the tour in which they turned the lights out and let us experience total darkness for a minute.
I visited MC like 25 years ago and I still have dreams about that room. One side of it sloped downwards and away and became lost in darkness but you could hear an underground river flowing from it. Very neat. Left an impression.