China releases report on rare coral reef blue hole in Huangyan Dao

BEIJING, June 25 (Xinhua) -- China's Ministry of Ecology and Environment released a report on a blue hole in Huangyan Dao in the South China Sea Thursday, which said the rare coral reef-formed feature is the first of its kind identified in China.

The opening of the blue hole covers an area of about 1,491.7 square meters and has a maximum diameter of 56.3 meters. It is 16.6 meters deep, with a funnel-shaped internal structure, a narrow bottom and distinct layers in water turbidity, according to the report.

Preliminary geochronological studies indicate that the blue hole was formed at least 3,200 years ago.

The report also noted that the blue hole and its surrounding waters are rich in biodiversity.