2 most interesting things to me were learning how long they crawled through a narrow space before it opened up to a big cabe with a waterfall within the mountain... something like 14 hours.

Then, learning how full of magnesium was. The tour guide said even a little bit would make you shit yourself

Then i started to think about the fact that if i had just found an underground waterfall, i would probably jump in if i didn't know any better..... then would've had to crawl out 14 hours the same way i came in....