Video footage has emerged showing the marine life inside an underwater sinkhole thought to be the world's deepest.

The newly found cave, located in the South China Sea, is 300.89 metres (987 feet) deep and 130 metres (426 feet) wide at the entrance, claimed researchers from China.

The one-minute-long video, which was released by state-run China Central Television Station yesterday, provides the first look into the mysterious underwater world.

A whole new world: Chinese state-run media yesterday released the first underwater footage of the sinkhole

Mystery unravelled: Chinese experts said they have found about 20 marine species in the underwater cave

Into the deep: Researchers from China made the announcement after they conducted 10-month field work

The finding was announced on July 22 by researchers from China after they conducted 10-month field work, reported People's Daily Online.

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.

It's situated near the disputed Paracel Islands, also known as the Xisha in Chinese and Hoàng Sa in Vietnamese.

Professor Yang Zuosheng from the Ocean University of China told China Central Television Station: 'Research into a blue hole can provide detailed records of how the climate or water level changes over tens of thousands of years.

'Once we have that data, we can deduce the pattern of evolution for climate changes in the South China Sea, including its eco-system, hydro-logical system and its landform.'

Dubbed the 'Yongle Dragon Hole' by the Chinese, the depth of the limestone cave is nearly the height of the 1,003-foot-tall skyscraper, The Shard.

Yongle is the name given by the Chinese to the atoll where the sinkhole is situated.

Beautiful: Chinese researchers claimed on July 22 they have found the deepest underground sinkhole

Giant under the sea: The depth of the mysterious sinkhole is nearly the height of The Shard in London

Mysterious: Located in the South China Sea, the cave measures 300.89 metres (987 feet) deep

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.

Field research: Chinese experts carried out field work between August in 2015 and June in 2016

Dive into the unknown: They also found tou the sinkhole is 30 metres (426 feet) wide at the entrance and about 36 metres (118 feet) wide at the bottom

Experts said they had also discovered about 20 marine species in the cave.

Underwater sinkholes are also known as blue holes.

Before Chinese researchers announced their findings, the world's deepest underwater sinkhole was thought to be the Dean's Blue Hole in Bahamas, which measures 202 metres (663 feet) deep.