Ключевые слова: abstract, adventure, ancient, background, big, bright, cave, cavern, caving, construction, danger, dark, deep, empty, entrance, expedition, exploration, explore, formation, geologic, geological, geology, grotto, ground, hole, inside, interior, landmark, landscape, light, limestone, mine, mountain, national, natural, nature, nobody, old, rock, speleology, spring, stone, sun, tourism, travel, tunnel, underground, wall, water,