It is part of a network of caves formed through lava flows from eruptions that occurred 100,000 to 300,000 years ago. A one Kilometer section is open to the public and this is what I trekked through early in the morning during a torrential downpour that was probably a significant contributor to the large pools of water on the cave floor and the large drops which fell constantly from the ceiling.
Having lugged my 4x5 up a mountain the day before and with a limited time span in which to photograph I decided to take the digital camera.
It is beautiful. I couldn't shake the thought that the spectacularly patterned floor I was walking on was once a moving hot river of molten rock and that the marks along the wall above my head were made by this same river at some particularly active point in it's history.
Given the early hour and the unfriendly weather, there was a surprising number of tourists also making the trip to view this rare geological feature. Mostly adorned with thin plastic macs they looked slightly ghostlike as the passed by the regularly placed floodlights, trying impossibly to avoid the puddles and avoid tripping on the uneven surface.
Around half way into the cave there was the rather surreal sight of an emergency telephone in it's own lit display case. My wife didn't think it was so bizarre but I thought that an intercom or 'help' button would have been fine, but this was a fairly old looking actual telephone. I half expected someone to stop and make a quick call - 'yeah hello dear? I'm gonna be a bit late for dinner. I'm in a cave...'
The main attraction though, is at the end of the cave where a raised walkway led to a chamber containing a dramatically lit column of rock. Actually a petrified lava flow this column hinted at the distant past, when molten rock dripped and poured through the ceiling of the cave and flowed along it's length. There are several examples of this troughout the world but this is the largest known lava column.
Well, I was impressed.
Then I had to make a plane back to Seoul which meant an extremely swift hike back to the entrance of the tunnel in time to make it to the airport.
Incidentally, in the dark and the damp I mangaged to drop my Nikon D200 on the floor while messing around with my tripod. I watched it bounce and roll a few times before nervously picking it up. Both Camera and lens were absolutely fine. I have a new found faith in the ruggedness of my camera...
I would also recommend the restuarant at the entrance to the park surounding the cave entrance. My breakfast consisted of some delicious dumplings as I waited for the lava tube to be opened to visitors.