The world’s deepest underwater sinkhole was discovered in the South China Sea. Researchers named it the ‘Dragon Hole’.
Researchers from China revealed that the limestone cave is 300.89 metres (987 feet) deep, which is nearly the height of the 1,003-foot-tall skyscraper, The Shard.
The world’s deepest underwater sinkhole was thought to be the Dean’s Blue Hole in Bahamas, which measures 202 metres (663 feet) deep, before Chinese researchers made the announcement on July 22.
The underwater sinkhole is located at 16.31 degrees north latitude and 111.46 degrees east longitude under the surface of the South China sea, according to China Radio International.
It’s situated near the disputed Paracel Islands, also known as the Xisha in Chinese and Hoàng Sa in Vietnamese.
Underwater sinkholes are also known as blue holes.
Chinese experts measured the dimensions of the blue hole during field research between August, 2015, and June, 2016, according to state-run Huanqiu.com.
With the help of equipment including sonar scanners, deep-sea current metres, underwater robots and underwater cameras, they found out the sinkhole is 300.89 metres (987 feet) in depth.
They also measured the width of the sinkhole, which is 130 metres (426 feet) at the entrance and about 36 metres (118 feet) at the bottom.
Experts said they had also discovered about 20 marine species in the cave.
In general, sinkholes form in limestone rocks and are caused by the passage of weakly acidic rainwater, according to Dr Mark Cowley from ListersGeo, a UK-based geo-technical and geo-environmental consultancy.
Limestone, a calcium-carbonate rich rock, is highly susceptible to dissolution by water containing carbon dioxide, said Dr Cowley.
This dissolution can create three common types of features within the limestone, grouped together under the generic term ‘dissolution features’.
These features include sinkholes, solution pipes and swallow holes.
Sinkholes are depressions at the ground surface caused by the collapse of overlying chalk or superficial deposits into underground voids created by dissolution.
Their shapes and sizes depend on the features of the underlying voids.