Ключевые слова: adventure, background, bridge, bulgaria, cave, eco, ecotourism, entrance, environment, eyes, famous, formation, geologic, geology, god, god eyes, gods eyes, hole, inside, karlukovo, karst, landmark, landscape, light, lovech province, lovech region, mountain, mysterious, mystery, mystic, natural, nature, phenomenon, prohodna, prohodna cave, river, rock, sight, sightseeing, speleology, stalactite, stalagmite, stone, tourism, travel, trip, underground, wall,