A group of scientists is gearing up, their hearts pounding. They’re about to descend into an unknown cavity on a mountainside in the middle of nowhere. They walk to its edge, lean back, and let gravity pull them into the earth.

It began as an ordinary day for this team of Chinese explorers, but it would end with a massive discovery. Upon finally reaching the bottom of the cavern, they laid their eyes on a magnificent landscape unlike anything discovered before.

Our planet keeps many secrets. These wonders are underground; they’re at the bottom of the ocean, in the treetops, and right in front of us. Only when the planet is ready, will it reveal them.

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Sinkholes are one of those wonders. They form all over the world, right underneath our feet. They form for hundreds of thousands of years, until one day Mother Nature shows us what’s beneath.

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One area that is teeming with sinkholes is the Fengshan County, in South Central China’s Guangxi Zhuang Autonomous Region. This wondrous landscape attracts tourists and visitors each year — and, for a good reason, scientists.

Xinhua

See, sinkholes form in what’s called a karst environment. Karst topography forms due to the erosion of rock types that are soluble in water. Additionally, water will dissolve certain types of rock over time due to the lack of drainage outlets in the bedrock.

When this happens, it will form a sinkhole or depression in the ground. Sinkholes can also form due to frequent freezing and thawing of subsurface water, and shoddy plumbing work. What does this have to do with Fengshan County?

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Fengshan County is a karst regision also known for its massive cave systems (there are 50 known caves in an area of 20,000 square feet)! Features like this lure scientists to the area from all over the world. 

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On October 4, 2018, 19 scientists from the Chinese Academy of Geological Sciences Institute of Karst Geology and the International Cave Association started a four-day expedition through the mountains that would lead them to an amazing discovery. 

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They were on a mission to reach a large sinkhole to record the exact dimensions and vastness of the cavern. When they finally reached the sinkhole, they geared up to propel down into the cavity.

Euronews / YouTube

They lowered themselves in using a single rope technique, which allows cave divers to cascade into the opening using one vertical rope. Dangerous? Potentially. But these professionals knew what they were doing.

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When the team finished their descent and placed their feet on solid ground again, they were awestruck at what they had just entered. They quickly realized this wasn’t just an ordinary sinkhole.

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This was a tiankeng, as the Chinese would say. Tiankeng translates to “skyhole,” sinkholes that reach down over 100 feet. There are less than 100 known tiankengs in the world. This made their research mission world class.

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The geologists and researchers were going to use a 3D scanning technique to examine the size of the main hall and all of the corridors that lied dormant underneath the ground waiting to be exposed. 

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They concluded the basement of the cavern dropped nearly 400 feet below the surface and stretched about 650 feet in length. The mouth of the cavern was approximately 330 feet wide. Meaning?

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This meant the volume of space they were standing in was a massive 236 million cubic feet!  There was also a sub-hall in the cavern that was almost 500 feet tall — and this was all underground. This meant that the cavern was big enough to fit the Great Pyramid of Giza, not once, but twice!

Incredibly, remember this was all hidden underground! This research discovery about the massive cavern created over thousands of years was monumental.

The team also discovered that the cavern might be in mid-collapse. Scans revealed that there is a network of underground rivers, which feed into the Panyang River.

South China Morning Post

And as the causes for sinkholes is often the erosion of rocks or subsurface water, the experts naturally supposed these underground rivers were probably responsible for the creation of the cavern — and the cause of the sinkhole.

Euronews

The team was praised for their discovery, but could not take all of the credit. Researchers from Hong Kong originally discovered the sinkhole, which enticed their team to further explore. In their honor, they named the cavern Hong Kong Haiting Hall.

Chinese Geological Survey

Scientists are hoping that their research conducted in the cave will help shed light on the extraordinary and ever-changing landscape of the Fengshan County region in China. 

Global Geoparks Network

 Watch as the team descends into Hong Kong Haiting Hall. You can explore the cavern more yourself  when you dig in to the riveting video below!