Ключевые слова: adventure, ancient, arch, archway, balkan, beautiful, boulder, bulgaria, cave, cavern, ceiling, cliff, dark, destination, devetashka, ecosystem, entrance, environment, famous, formation, geology, hole, indoor, inside, interior, landmark, landscape, large, limestone, nature, open, rock, scenic, speleology, stone, tourism, tranquil, travel, tunnel, underground, wall,