Geomunoreum Lava Tube System is a series of lava tubes that originated from the eruption of Geomunoreum, a parasatic cone. Geomunoreum has an altitude of 456 meters and with lava tubes spreading out in a streamlined shape, its lava tube system is the largest of its kind on Jeju Island. The name is said to have originated when the local islanders called the cone "Geomun," which is translated to “black,” referring to the dense forest formed on the crater. However, according to researchers and linguists, the term "Geomun" may have originated from a word from the Gojoseon period which were used to refer to deities, inferring that the name Geomunoreum actually means "holy hill."

Geomunoreum Lava Tube System consists of roughly 20 lava tubes that follow the cone's slope to the northeast, stretching out all the way to the shore. Among these tubes, Bwengdwigul, Mangjanggul, Gimnyeonggul, Yongcheondonggul, and Dangcheondonggul Caves are inscribed as a UNESCO World Natural Heritage.