China is home to some of the most mysterious geological formations on Earth. The South China Sea boasts the mythical “Dragon hole,” thought to be the deepest underwater sinkhole on Earth. In China’s remote northwest, meanwhile, a “gateway to Hell” has opened, revealing a burning pit of molten lava seemingly just below residents’ feet. Another strange spot stays frozen year-round, even in warm summer temperatures. Now, geologists in China have discovered a rare geological phenomenon that could offer a glimpse into a completely unknown ecosystem and landscape.

The cluster is the largest-known sinkhole cluster in the world.

According to a report by China Daily, government officials in Shaanxi province discovered a rare cluster of massive sinkholes while conducting a geological survey of the Qinling-Bashan mountain range. The cluster of forty-nine sinkholes is spread over a 5000 square kilometer (~1900 square mile) range across four counties in one of China’s rural central provinces. So far, the largest of the cluster has been found to have a width of 1,706 feet (~500 meters) and a depth of 1,050 feet (~300 meters).

Many of the sinkholes could provide a glimpse into never-seen-before ecosystems.

Geologists estimate the sinkholes formed over roughly half a million years as underground bodies of water eroded porous bedrock such as limestone. The same geological process is responsible for China’s unique karst mountain landscapes. Several unique species of plants and animals have been found living among the sinkholes, including Chinese flying squirrels, but a complete biological survey has yet to be conducted. Already, the discovery of the sinkholes is filling in some of the gaps in geological knowledge about the formation of this ancient landscape.

China’s karst landscape was formed by the erosion of limestone, sandstone, and other porous stone.

Naturally, local officials are already eyeing the area as a potential tourist destination. Perhaps they could find a way to spin the sinkholes as the home of that Chinese “dragon” reported in a viral video a few months back. Stranger Chinese tourist traps have been built, after all.