The Worlds Below Phong Nha - Ke Bang National Park

At one point deep inside the Tu Lan cave system, the members of our tour all pointed our headlamps up at a huge column. The solid sediment looked as liquid as a clock in a Salvador Dali painting. No wonder people are so drawn to touch formations in caves – it’s hard to believe that they are solid. You want to poke it with your finger just to make sure. Luckily for us, the cavern burrowing through the mountain above us and the sharp stalagmites hanging over our heads were very solid. Barring an earthquake, we could have sat in our cave for a thousand years and not notice a single change. With the exception of a bat fluttering by every once in a while, caves are basically controlled laboratories for nature’s geological experiments. While I was at Phong Nha National Park in north-central Vietnam, I spent a fair amount of time deep inside these caves, so I had some time to think about it. Here are my observations about spelunking in the wilds of Vietnam.

View of Phong Nha and the Dr. Seuss mountains behind it

Cave Cricket

First, walking through a cave is a lot like diving on a coral reef. I started realizing this after our guide described a cave formation as looking like a piece of coral. The same subterranean forces that shape the rocks under mountains seem to have the same personalities as the submarine forces that shape the underwater world. Beyond the visual similarities between formations and coral reefs, the whole experience has a lot of parallels. Going into a cave requires a similar checklist as descending below an ocean surface: secure and check all of your gear; do a head count to see how many people are in your group; identify your entry point and then descend. Like diving, descending into caves can be pretty technical and you tend to be really focused on just picking your way down the rocks. When I dive, I’m usually too preoccupied with equalizing my sinus pressure and maintaining a constant descent to really notice what’s going on around me. But then, you reach the bottom and realize that you’ve landed in a different world. You start noticing fish/bats going back and forth overhead; you crane your neck upward to see the coral/rock features tower over head and, as you start traversing the floor of the sea/cave, you start noticing little critters in the crevices and start sticking your mask/headlamp into little corners to watch cave crickets/sea urchins hanging out on their rocks.

You get the same kind of tunnel vision in a cave as underwater. Both worlds require you to observe through a kind of window – either a headlamp in the cave or through a mask underwater. This forces you to process your surroundings piecemeal – it’s difficult to get the wide panoramas that we’re used to with peripheral vision up on the surface. Every once in a while, you have to look up and confirm that there is indeed something above. This tunnel vision helps to maintain some mystery in your surroundings, but it also helps you focus on what’s right in front of you. Sometimes peripheral vision can be a distraction. Up on the surface, our wide field of vision just gives us too many things at once. It’s distracting! Below the surface, the visual field is more suitable to those of us who don’t like to multi-task.

A drop of water forming a stalactite

Also, coral reefs and Vietnamese caves aren’t as far removed as you might think. The layers of rock that form the walls of the caves came from layer-upon-layer of coral reef, underwater plants and life that covered the sea floor millions of years ago. Like most of the world, the caves burrowing under mountains were once sea floors. Some people think caves are haunted. I agree with them, but I don’t think that caves haunted by human spirits – they’re haunted by the billions of pieces of compressed sea-life that make up the walls and ceilings holding up the millions of tons of mountain directly overhead.

View of the entrance to Ken cave from our campsite

Second, I can totally see how previous human civilizations could have mistaken caves for hell. The surface of Phong Nha national park is remarkable for its natural beauty. The karst landscape makes for dramatic mountains that rise up out of nowhere and sheer cliff faces framed in lush jungle. The sun shines brightly, rivers flow through the valleys and humans survive on what the earth provides. But look a little closer at one of those cliff faces or follow a river upstream far enough and you’ll find a gaping hole in what you thought was a relatively solid earth surface. They are dark, mysterious places that don’t seem to provide much support to life – except that bats fly out of their gaping mouths every dusk to prowl the night skies. Caves are weird places and only the bravest/fool hardy of people would venture to go into one without a reliable light source.

Lush rice fields on the surface

Imagine a medieval adrenaline junky venturing out of the security of his village to go explore one of these holes in the earth. Maybe he has a torch as a light source. He can’t convince anyone else to leave the village to go on this asinine adventure, so his discoveries can only be translated through the perhaps faulty wiring of his own consciousness. He stumbles his way down sharp, loose rocks, eventually losing the light from the entrance. At the bottom of the cave, darkness is absolute. If it weren’t for his torch, he couldn’t see his own hand in front of his face. The weak light from his flame shows bizarre, twisted formations of rocks. Stone daggers thrust up from the floor and hang down from the ceiling, threatening to impale him at any second. Blobs of collected sediment protrude from the cave walls, eerily resembling slimy monsters that he’s heard described by local fishermen who have sailed far out to sea. He hears noises but they are unfamiliar and he cannot determine their source. Going into a cave is to go into a different, unexplainable world that is so physically close to our own but so far removed. The lush colors of abundant life that make up the outside world immediately turn into a deathly grays and browns below the surface. If our explorer can’t find his way back to the mouth of the cave, if his light goes out, surely he’ll die down there.

I can’t imagine anything closer to the physical manifestation of hell than going down into a cave. Naturally, there aren’t devils dancing around with pitchforks, but if you look at some of those formations from the right angles, the stalagmites and stalactites look like pointy incisors attached to gigantic jaws ready to chomp down on anyone foolish enough to get in their way. With the right mixture of fear, imagination and a few hundred years of creative embellishment, those caves become our modern portrayal of hell. But even if Dante and John Milton were fooled, I’m not. I know that caves are really just spooky abandoned coral reefs.

Nautilus fossil/ghost in the cave wall