Manjanggul Cave is one of the longest lava tubes in the world, stretching over 7 kilometers underground. It is part of Jeju Island's UNESCO World Heritage sites. Visitors can explore approximately one kilometer of the underground passage, witnessing stunning lava formations, stalagmites, and stalactites. The cave maintains a constant temperature of about 11-21°C year-round. At the end of the accessible section stands a massive 7.6-meter lava column, the largest of its kind in the world.