Ключевые слова: cave, cavern, caverns, caving, cold, crystal, dark, darkness, effect, elow, erosion, explore, formation, frost, geological, growth, hall, hole, ice, inside, landscape, limestone, mexico, mine, mineral, mountain, national, natural, nature, rock, speleology, stalactite, stalagmite, stone, subterranean, tourism, travel, underground, underworld, view, water,