Exploring Asia’s Longest Lava Tube

During my week in Jeju I’ve often heard it called a “volcano museum,” since the small island—just 45 miles (73 kilometers) long—is jam-packed with volcanic superlatives.

Created by a massive eruption about two million years ago, Jeju is home to 368 small mountains and more than 160 lava tubes—a rare combination on such a tiny piece of land. Evidence of volcanoes is everywhere, from the basalt sidewalks and old-grandfather statues to the many peaks that are almost always in view (even from my little hostel window).

Inside Manjanggul Cave. Photos by Christine Dell’Amore

Jeju also has the longest lava tube in Asia, Manjanggul Cave, above, which snakes underground for about 8.3 miles (13.4 kilometers), a little less than a mile of which is open to the public. I’d only had a general idea of lava tubes before, but learned that they’re formed when molten lava below earth’s surface begins to slow and solidify, creating long, tunnel-like caves.

According to the U.S. National Speleological Society:

“Because  lava  tubes  are  formed  by  volcanic  processes,  they  are  very different  from  the  more  common  and  better  known  limestone  caves. Magma, super-heated deep in the earth, rises through overlying material that forms the earth’s crust. Eventually this molten rock may reach the  surface and erupt as lava.”

I felt I couldn’t leave Jeju without seeing this UNESCO World Heritage Site, so I hired a taxi yesterday to take me the hour or so’s drive from the conference center.

Walking down the basalt steps into the belly of the cave, you’re transported into another world—a gigantic, at times 75-foot-tall (23-meter-tall) space that seemed to stretch on for eternity. The ceiling and walls were almost perfectly rounded, almost like someone had scraped out the contents in the same way you hollow out a pumpkin.

Stalactites on the ceiling and walls of the cave.

My eyes struggled to adjust in the darkness—only a few ground lights illuminated the path of solidified lava, whose bumpy, corduroy-like texture made walking difficult. The park had installed some colorful lights to highlight the higher parts of the tube ceiling—called cupolas—giving it a colorful, cathedral-like atmosphere.

Along the trail signs explained various types of lava formations—stalactites, formed when the tube ceiling melts from the heat of lava flowing into the cave, and my personal favorite, the lava toe, which occurs when lava flows into a hole in the lower level of the cave and hardens into a shape that resembles the toe of an elephant.

As I picked my way along the uneven ground, water constantly dripped from the ceiling, sometimes hitting me square in the eyeball. I kept my eye out for critters inside the cave, including bats and spiders, but they stayed out of sight.

Manjanggul cave’s lava column, lit by colored lights.

At the end of the path was the star attraction—a lava column, created when lava dripped from a hole in the ceiling. At 25.6 feet (7.8 meters), it’s the tallest lava column on Earth.

It was the perfect note on which to end my experience at the World Conservation Congress—appreciating nature in one of the wonders of the world.

This is my last post from Korea, but keep an eye out for follow-up posts in the future. Thanks for coming along on my adventure!

Christine Dell’Amore, environment writer-editor for National Geographic News, is reporting from the IUCN World Conservation Congress in Jeju Island, South Korea.


Meet the Author
Christine Dell'Amore, environment writer/editor for National Geographic News, has reported from six continents, including Antarctica. She has also written for Smithsonian magazine and the Washington Post. Christine holds a masters degree in journalism with a specialty in environmental reporting from the University of Colorado at Boulder. Her book, South Pole, was published in 2012.