Researchers have explored a blue hole in the waters of the Paracel Islands in the South China Sea, state broadcaster CCTV reported.
According to CCTV, data obtained by an underwater robot and depth transducer showed that the depth of the hole, named by the Chinese as Yongle Blue Hole, is about 300m, making it the deepest blue hole ever to be discovered.
In areas beyond the reach of the divers, the robot was able to measure the temperature, salinity and dissolved oxygen level of the water, the state broadcaster claimed.
It was found that there is no oxygen in waters deeper than 100m in the hole.
The Paracel Islands are claimed all or in part by China, Vietnam and several other Asian countries.
They are known as Xisha in Chinese and Hoang Sa in Vietnamese.