Manjanggul is a remarkable lava tube located on Jeju Island in South Korea. It is one of the longest lava tubes in the world, stretching approximately 7.4 kilometers. Formed by volcanic activity, the tube features stunning rock formations, including lava stalactites and stalagmites, which showcase the natural beauty of the underground environment. The Manjanggul Lava Tube is a UNESCO World Heritage site and is open to the public for exploration. Visitors can walk through a section of the tube, which is well-lit and accessible, allowing them to experience the unique geological features and learn about the island's volcanic history.