Sansha Yongle Dragon Hole, located around Yongle atoll of the Xisha Islands in the South China Sea, is known as the world's deepest blue hole - with a depth of 300 meters - and a rare marine lab.

Experts have suggested the local government to establish a natural reserve to protect the site’s original landscape, water environment, and biodiversity.

China has been strengthening environmental protection in Sansha City, which was established in 2012, to administer islets and reefs in Xisha, Zhongsha and Nansha islet groups as well as waters in the area.

A research group of the Chinese Academy of Sciences’ South China Sea Institute of Oceanology set two restoration locations on the Xisha Islands and successfully bred over 6,000 corals.

Due to excessive fishing, marine pollution and damage to spawning sites, the number of sea turtles has drastically decreased each year. To protect sea turtles from extinction, a station was built to allow safe spawning.