Tips:
-Don't touch anything but the floor, watch your head. That's where rock-fall begins, and the area rock is unstable.
-Don't speak loudly, If I were bats, I'd be in there. Can also effect rockfall. See: resonance.
-Don't move close together: If something happens to one of you, you don't want it happening to both of you.
-3 people is ideal, one to stay outside and run if needed.
-These are prone to flash flooding, mind the weather. I've seen signs of wicked water movement from last weekends showers. This weekend looks worse. One of the reasons I plan to wait for autumn.