The Manjanggul Lava Tube is located in Gimnyeong-ri, Gujwaeup, Jeju City. At up to 23m wide, 30m high and 8.928km long, it is the 12th-longest lava tube in the world and the second longest on Jeju island. It is regarded as having significant scientific and heritage value, owing to its excellent condition of preservation despite its age of formation.
Lava stalactites and lava stalagmites, lava columns, lava flowstone, lava helictites, lava blisters, cave coral, benches, lava rafts, lava bridges, lava shelves, grooved lava striations, and ropy lava are well-preserved. Among them, a lava column of 7.6 m is the largest known in the world. There are three entrances and No. 2 heading southward is open to the public.
Wikipedia https://en.wikipedia.org/wiki/Manjanggul
Phone +82-64-710-7903
Coordinates 33°31'44.175" N 126°46'17.035" E