Ключевые слова: background, beautiful, bulgaria, cave, cavern, caving, dark, destinations, enormous, entrance, famous, formation, geology, harmony, heritage, hole, horizontal, huge, idyllic, interior, landmark, landscape, large, light, limestone, locations, national, nature, panoramic, park, phenomenon, place, ridge, rock, sandstone, scene, scenic, stalactite, stalagmite, stone, thailand, tourism, tranquil, travel, tunnel, underground, view, wide, world,