Ключевые слова: adventure, astonishing, beauty, big, cavern, cellar, dark, discovery, erosion, exploration, exquisite, fascinating, geological, geology, gorgeous, greatness, huge, illuminated, impressive, intricate, kebang, limestone, magnificent, majestic, mysterious, natural wonder, nature, paradise cave, phong nha, rock, sculpture, shadows, spacious, spectacular, speleothem, splendor, stalactite, stalagmite, subterranean, tourism, training, travel, underground, unique, vietnam, wonder, wonderful,