Paracel Islands, in shallow bank to the east from Pattle Island, near Discovery Reef.
|Dimension:||VR=301 m, D=129 m.|
Shiguo Wu, Xinyuan Zhang, Zhen Yang, Tuoyu Wu, Jinwei Gao, Dawei Wang (2016):
Spatial and temporal evolution of Cenozoic carbonate platforms on the continental margins of the South China Sea: Response to opening of the ocean basin
SEG Interpretation, August 2016.
Tiegang Li, Aiping Feng, Yanxiong Liu, Zhenhong Li, Kai Guo, Wenzheng Jiang, Jun Du, Ziwen Tian, Wenxue Xu, Yang Liu, Yanru Wang (2018-11-20): Three-dimensional (3D) morphology of Sansha Yongle Blue Hole in the South China Sea revealed by underwater remotely operated vehicle Scientific Reports. 8 (1): 1–9, Article number: 17122 (2018). doi:10.1038/s41598-018-35220-x. ISSN 2045-2322 online
Linping Xie, Baodong Wang, Xinming Pu, Ming Xin, Peiqing He, Chengxuan Li, Qinsheng Wei, Xuelei Zhang, Tiegang Li (2019-02-01): Hydrochemical properties and chemocline of the Sansha Yongle Blue Hole in the South China Sea Science of The Total Environment. 649: 1281–1292. doi:10.1016/j.scitotenv.2018.08.333. ISSN 0048-9697 DOI pdf
|As far as we know this information was accurate when it was published (see years in brackets), but may have changed since then.
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|2015-2016||explored by a team of Chinese researchers from Sansha Ship Course Research Institute for Coral Protection.|
The Dragon Hole in the South China Sea is the deepest blue hole on Earth. With a depth of 300 m there is currently no theory how it might have formed. Blue holes are typically collapse dolines formed by the collapse of a cave system. As the sea level was once 120 m lower than today, there were caves formed draining to the sea, which were later submerged and filled with water. However, the sea level was never 300 m below today, so it is either not a karst cave or there was tectonic subsidence in recent times of at least 180 m. Another possibility would be hypogene cave development, commonly with a volcanic source of carbon dioxide or with sulfuric acid from the bitumen rich layers below.
The blue hole was explored by a team of Chinese researchers from the Sansha Ship Course Research Institute for Coral Protection in 2015 and 2016. They used a robot named Video Ray Pro 4 and reached the bottom at 300 m. The upper 100 m of the hole were found rich with sea life, but below this border, the water is oxygen-free and devoid of life. It was formed inside 1200 m thick Miocene limestone.
The blue hole was known to local fishers for centuries. Local legend knows that the Monkey King found his golden mace here, because this is the eye of the South China Sea. The Journey to the West was published in the 16th century and is one of the four great classical novels of Chinese literature.
It is not possible to visit the Dragon Hole, because the Chinese Government has prohibited fishing and tourism in this area.