There are lots of stories. People will stab others with their dive knife to get their air tank.
One lady, a very experienced cave diver, had a malfunction and then ran out of air. When they found her she had clawed at the rock with her fingers hard enough to rip the fingernails and flesh off the ends of her fingers.
I taught SCUBA diving for years, but never had the opportunity to go cave diving. I would think it would be wise to carry a pony tank in case of emergency. I don’t know about navigation. I can navigate in the ocean with or without a compass using surge direction, sand ripples and pilotages, but what do you use in a cave? Cord?