Ключевые слова: black cave, buoyancy, cave, cave diving, cavern, cavern diving, cenote, cenote angelita, cenote mexico, cenotes, cenotes mexico, depths, dive, diver, divers, dives, diving, diving course, diving scuba, grand cenote, scuba, scuba dive, scuba diver, scuba divers, scuba diving, speleology, technical diving, underwater cave, underwater diving, wreck diving,