China's Sansha city has decided to allocate 5 million yuan ($748,000) annually for maritime environmental conservation in the next three years.

A first round of special environmental funding worth 1 million yuan was earmarked on Saturday for exploration of the newly confirmed world's deepest underwater sinkhole, or blue hole, in the Xisha Islands. The blue hole in Yongle, a major coral reef, is 300.89 meters deep. It is known as Longdong, or "Dragon Hole".

The funds will be used to support scientific research and development of new methods and equipment in environmental protection, said Shi Guoning, a senior official in Sansha's Land Resources and Environmental Protection Bureau.

Over the past four years, the city has invested more than 30 million yuan in the treatment and restoration of reefs and islets, according to the bureau.

It has also organized the breeding of fish and sea turtles, which have been released into the sea six times. In addition, it has cracked down on the illegal capture of birds, according to Xu Zhifei, vice-mayor of Sansha.

Sansha was officially established in 2012 to administer the Xisha, Zhongsha and Nansha island groups and their surrounding waters in the South China Sea.