Of course some humans can hold their breath for 5 minutes, which could absolutely get you in trouble in a cave.. Some of the caves we dive have openings to the surface along the way.. they look STUNNING cuz the sunlight comes through the openings like laser beams.. a FEW caves have enclosed "rooms" in which you can surface and hang out for a while.. those rooms always get me in trouble.. for some reason, surfacing and then going back down causes me to have extreme difficulties in equalizing my ears - or "popping them" as you submerge.. you know how it hurts your to dive to the bottom of a pool - its gets worse the deeper you go until you blow out your eardrums.. Next time you dive to the bottom of a pool, halfway down hold your nose closed with one hand and blow to pop your ears.. if you go too deep, the pressure will be too much and they won't pop, so come up a couple of feet and try again..
Anyways, Taj Mahal in Mexico has a room like that.. we surfaced, the guide and my wife went down to continue the dive, but I could EQ my ears.. I watched them swim off around the corner and I was stuck - couldn't get out.. of course I could surface in the room for as long as I wanted, but the EQ things happens in the middle of dives, as well, when you hafta go deeper.. if both passages OUT of the cave require you to go deeper and you can't EQ, eventually you'd run out of air, so you HAVE to blow your eardrums out in order to not drown.. luckily I have had that happen, yet.. Anyways, I eventually got my ear to "sqeeeeeaaakk.. POW!" and it popped.. when that happens, it hurts like HELL..
Some of the caves we dive have human bones in them from the old Mayans when the cave wasn't flooded.. Some have animals Bones.. one is name Pet Cemetery due to the animal bones in it.. If you ever saw the movie Sanctum, a guy breathes the air pockets trapped against the roof of the caves.. one of these days I will try it.. but, no telling how long that air has been there and more than likely is another divers carbons dioxide - or bubbles from the other end.. lol
Friendship is like peeing your pants.. Everybody can see it, but only you can feel the warmth..