One of the finest lava tubes on Earth, running under Jeju Island in South Korea, part of a UNESCO World Heritage volcanic system. A kilometre is open to walk, ending at a seven-metre lava column, the tallest known anywhere, with lava stalactites and rafts along the way. Korea’s limestone country to the north holds Hwanseongul, its largest cave. PUBLIC, Jeju, South Korea.
South Korea
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