Ключевые слова: aquifer, bat cave, blue, cave, cave diving, cave systems, cavern, cavern diving, cenote, clear, danger, dangerous, diving, dos ojos, groundwater, limestone, mexico, overhang, playa del carmen, rock ceiling, rocks, scuba, sinkhole, sketch, sketchy, snorkel, snorkeling, snorkle, stalagmite, stalagtite, turquoise, underwater, water, yucatan peninsula,