Dragon Hole is the deepest known blue hole in the world at 300.89 metres (987.2 ft) deep, and is located about 25 kilometres (16 mi) south of Discovery Reef in the Paracel Islands. Blue holes are characteristically dozens of metres deep and generate a distinctive blue colour when seen from above.
Dragon Hole is almost 100 metres (330 ft) deeper than Dean's Blue Hole in the Bahamas. There are several fresh water sinkholes on land that are deeper than Dragon Hole. These include Mexico's Zacatón (335 metres (1,099 ft)), Pozzo del Merro in Italy (392 metres (1,286 ft)), and Hranice abyss in the Czech Republic (404 metres (1,325 ft)).
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- "China Exclusive: South China Sea "blue hole" declared world's deepest". New China. Xinhua News Agency. 23 July 2016. Retrieved 29 July 2016.
- Mazza, Ed (29 July 2016). "'Dragon Hole', World's Deepest Blue Hole, Discovered In South China Sea". Huffington Post. Retrieved 29 July 2016.
- "Deep Blue Hole Found in South China Sea". The Wall Street Journal. Dow Jones. 28 July 2016. Retrieved 29 July 2016.