Sơn Đoòng Cave

Imagine a place where cool mist hangs in the air like a soft blanket, where you can hear the deep roar of a river you cannot see. Sunbeams slice through the darkness from high above, lighting up a lush, green jungle on the ground below you, even though you are deep underground. This world, big enough to hold an entire city block of skyscrapers, was a secret for millions of years. I am a world hidden beneath the forests of Vietnam. I am Sơn Đoòng Cave, which means Mountain River Cave.

I wasn’t always this grand. My story began a very long time ago, between 2 and 5 million years ago, when the patient Rao Thuong River found a path beneath the earth. It flowed through cracks in the limestone rock, and drop by drop, it began to dissolve the stone, carrying it away. This process was incredibly slow, like a patient artist working on a giant sculpture for millions of years. As the river carved me wider and taller, water dripping from my ceiling created colossal stone formations. Some grew down from the ceiling like giant icicles, called stalactites. Others grew up from my floor like strange towers, called stalagmites. Some of these are now over 262 feet tall. A very long time ago, parts of my ceiling grew weak and collapsed, creating two enormous holes that are like skylights to the world above. These openings, called dolines, let the sun pour in, and over thousands of years, a whole jungle took root and grew in my belly.

For most of my long life, I was known only to the monkeys and birds that flew through my dolines. Then, one day in 1990, a local man named Hồ Khanh was walking through the jungle looking for wood. A fierce storm rolled in, and he scrambled to find shelter. He found it near a large opening in a cliff. As he huddled there, he felt a powerful wind rush out from the darkness and heard the loud roar of my river. He was curious, but the entrance was steep and the sounds were intimidating, so he didn't dare go inside. He marked the spot in his memory, but the jungle is a tricky place. For the next eighteen years, he tried to find me again, but the path was lost. I remained a secret, a story only he could tell, a giant world waiting patiently in the dark.

Hồ Khanh never forgot about the wind and the roaring water. He kept searching, and finally, in 2008, he rediscovered my entrance. He knew this was too important to keep to himself. He contacted a team of experts from the British Cave Research Association, and on April 10th, 2009, he led Howard and Deb Limbert to me. The explorers clipped onto ropes and rappelled down into my misty darkness. They were speechless. Their small headlamps could not even reach my ceiling or my farthest walls. They walked for days, discovering my underground river and the jungle they named the Garden of Edam. Their journey was finally stopped by a huge, slippery wall of calcite that they named the Great Wall of Vietnam. They had to turn back, but they returned a year later, in 2010. This time, they climbed the wall, and when they reached the other side, they could finally prove what they suspected. I was the largest cave in the entire world.

Being the largest cave in the world is a big responsibility. My ecosystem is unique and fragile, from the sightless fish in my river to the rare plants in my jungle. To protect me, only a very small number of visitors have been allowed to see my wonders since tours began in August of 2013. I am not a simple tourist spot; I am a living, breathing piece of the Earth’s history. I am a reminder that our planet is full of hidden beauty and power. My story shows that there are still incredible wonders left to find, and I hope I inspire everyone to explore, respect, and care for our amazing planet.