A rare coral reef blue hole discovered in the South China Sea is a "natural archive" of climate and biodiversity history, with surveys revealing rich coral and fish species thriving in and around the site, said Pei Xiaofei, spokesman for China's Ministry of Ecology and Environment, on Thursday in Beijing.
The ministry released a report on the blue hole in Huangyan Dao in the South China Sea at a press conference, 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.
A rare marine blue hole has been discovered in the South China Sea. Scientists say the site could yield new insights into the evolution of marine ecosystems and support future conservation efforts.
Often called the "eyes of the ocean", marine blue holes are among the planet's rarest geological formations. At the press conference, Pei highlighted the remarkable biodiversity flourishing in and around the blue hole.
"The blue hole is home to typical coral reef species, including corals, giant clams, fish, sponges and sea anemones. Green sea turtles, a nationally protected species, have been observed inhabiting the blue hole and its entrance area," Pei said.
Researchers say the blue hole formed over the long-term growth of coral reefs. Preliminary geochronological studies indicate that it was formed at least 3,200 years ago.
Surveys conducted over the past two years in the surrounding waters recorded 165 species of reef‑building corals and 184 species of fish.
"Blue holes are natural archives of geological and environmental change, historical climate records, and biodiversity evolution, and therefore possess significant ecological and scientific value," Pei said.
The ministry says the findings highlight the positive results of ecological protection efforts in the waters around Huangyan Dao.
In 2025, China established a national nature reserve there to further strengthen marine conservation.
Long-term studies are now underway to uncover more of the blue hole's secrets. Scientists say the research will deepen our understanding of these underwater ecosystems and help guide future conservation efforts.
Newly discovered rare blue hole in South China Sea serves as "natural archive": surveys
