Authorities in Sansha city in the country's southernmost Hainan Province, has banned tourism and fishing to protect the environment around the area known as "Dragon Hole", which China said is the world's deepest blue hole, China Daily reported.
According to a notice issued by the management committee of the Yongle Islands in Sansha, activities by individuals and group within one nautical mile around Longdong or the "Dragon Hole" are forbidden.
Activities such as scientific expeditions and environmental protection programs must first get government approval, the notice said.
The blue hole is a major coral reef more than 300 meters deep and believed to be the deepest of its kind in the world. Blue holes, or underwater sinkholes, are darker blue in color and gets darker as the water inside gets deeper.
According to the report, the notice, which was posted on the Sansha government's website on Saturday, Oct. 8, aims to protect the blue hole and the neighboring coral reef system.
Track Ocean, a private research organization has investigated the sinkhole several times between August last year and in June this year. It measured the sinkhole's diameter which is about 130 meters while the depth measures 36 meters.
The sinkhole, which is 100 meters deeper than Dean's Blue Hole in the Bahamas, has important scientific value, Yang Zuosheng, a professor at Ocean University of China in Qingdao, Shandong Province, said.
Yang said that crucial information can be found in the coral reef's 300-meter-deep formation, where researchers can study how changes in global climate and sea level affect the local waters.
A report by Hainan Daily said that research program on the sinkhole was the first project supported by Sansha's special fund for maritime ecological protection.
The Sansha government established a committee in July 2013 to manage the Yongle Islands, which are part of the Xisha Islands, including the surrounding waters.
Guo Yong, deputy director of the committee, said the notice issued on July 28, shows that Sansha values maritime environment. He said the committee has spent more than 20 million yuan ($3 million) to restore the diversity of marine life in the area. They have also released various species of young fist sea cucumbers around the reef.