UNESCO calls the Geomunoreum system the finest lava tube cave system in the world, and it is the reason Jeju Island is World Heritage. Molten rock drained out from under its own cooling crust and left tubes running for miles, hung with stalactites and mineral crusts that formed a second time from seashell sand blown in above; Yongcheon Cave holds an underground lake, the Millennium Lake. The listing covers 9,475 hectares in three parts, this tube system, the Hallasan reserve and the Seongsan Ilchulbong tuff cone. Manjanggul is the tube that is open to walk. South Korea.
South Korea
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