The volcanic island of Jeju, is well located 130 kilometers from the southern coast of the Korean Peninsula, has a widespread system of lava tubes. These natural conduits through which magma once flowed are now empty caves that are some of the largest in the world. However these caves, apart from providing opportunities for scientific research, are popular sightseer destinations.
The most inspiring is the Geomunoreum Lava Tube System formed by the flow of basaltic lava when the Geomunoreum volcano erupted more than 250 thousand years ago. Amazingly the volcano has an elevation of 456 meters and lava flowed down to the coastline 13 km away, and while doing so, created plentiful lava tubes. The Manjanggul Lava Tube represents the largest cave in this system. Because it is stretches 8,928 meters and its passages are up to 30 meters high and 23 meters wide.
manjanggul-lava-tube-4The insides of the tube is ornamented with multi-colored carbonate decorations and countless cave formations commonly found in lava tubes. They’ve included lava stalactites and lava stalagmites, lava columns, lava flowstone, lava helictites and lava blister, cave corals, benches, lava raft, lava bridges, lava shelves and striations. So at the end of the one of the passageways open for tourists, is a gigantic lava column shaped when a large amount of lava spilled from the upper level down to the lower level. This menacing column stands 7.6 meters high and is the biggest known in the world.
Moreover some 30,000 common bent-wing bats (Miniopterus schreibersii) have taken eternal residence inside the tube, establishing the largest colony of bats so far recognized to be living in Korea. Almost 38 types of cave creatures have been recognized inside the Geomunoreum Lava Tube System, the most common of which is the Jeju cave spider (Nesticella quelpartensis).