Manjanggul runs 8.928 km under the northeast of Jeju Island, up to 23 metres wide and 30 metres high, which makes it the twelfth longest lava tube in the world and the second longest on Jeju. It is the only cave of the Geomunoreum Lava Tube System open to the public, and that system is generally reckoned among the finest anywhere. The whole thing is inscribed by UNESCO as part of Jeju Volcanic Island and Lava Tubes.
Its lava left its own decoration behind. Limestone caves are hung with formations built by dripping water; here the shapes are made of the rock itself, frozen mid-movement. There are lava stalactites and lava stalagmites, lava columns, lava flowstone, lava rafts and lava shelves. One of the columns stands 7.6 metres, and it is the largest lava column known anywhere in the world.
There are three entrances. Visitors use only the second, which faces south, and can walk about a kilometre in; the rest is closed, and for good reason. Entrance three holds the best habitat for cave life, and the lower main tube between entrances one and two is where most of the cave's creatures live. Manjanggul supports more life than anything else in the Geomunoreum system, including the Jeju cave spider. Above entrance two there are at least 30,000 common bent-wing bats, the largest bat colony confirmed anywhere in Korea.
It is cool and damp inside, the floor is uneven wet basalt, and the walk is a straight there-and-back kilometre. Jeju itself is a volcanic island, so the tube is one piece of a much larger story you can see above ground.
South Korea
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