That exploration has not been without loss.

Cave diving accidents in the Yucatán system and elsewhere have killed experienced and well-prepared divers — the environment does not forgive mistakes, and even divers with extensive training and experience have died in underwater cave systems.

The cave diving community manages this risk through rigorous training standards, redundant equipment, the use of guideline reels that allow divers to follow a physical line back to the entrance even in zero visibility, and the practice of turning back when gas reserves reach specific thresholds.

Alberto Nava and the other divers who discovered and documented Hoyo Negro were operating within this tradition and adhering to its safety protocols.