The Geomunoreum Lava Tube System is located between Seonheul-ri, Jocheon-eup and Weoljeong-ri, Gujwa-eup, Jeju City, Jeju-do. This lava tube system refers to a series of lava tube caves formed while basaltic lava flow which had erupted several times from the Geomunoreum volcano (which has an elevation of 456 m) flowed in a north-northeast direction, down to the coastline for about 13 km. It is estimated that it was formed between about 100 and 300 thousand years ago.
Lava tubes so far included in the Geomunoreum Lava Tube System are the Seonheul Vertical Cave,Bengdwigul Lava Tube, Bukoreumdonggul Lava Tube, Daerimdonggul Lava Tube, Mangjanggul Lava Tube, Gimnyeonggul Lava Tube, Yongcheondonggul Lava Tube, and Dangcheomuldonggul Lava Tube towards the sea. However, it is estimated that more tubes will be found. Bukoreumdonggul Lava Tube, Mangjanggul Lava Tube and Dangcheomuldonggul Lava are designated as natural monuments. Although these lava tubes are extremely large and ancient, the internal morphological features are well-preserved and the inner scenery is considered to be outstanding. As a result, "Jeju Volcanic Island and Lava Tubes" are UNESCO World Natural Heritage Sites.