Donghai Island (simplified Chinese: 东海岛; traditional Chinese: 東海島; pinyin: Dōnghǎi Dǎo; French: Île de Tan-Hai) is an island in the southeast part of the urban area of Zhanjiang, Guangdong, People's Republic of China. It is part of Mazhang District. It has a coastline of 159.48 kilometres (99.10 mi), with a total area of 286 square kilometres (110 sq mi), making it the largest island in Guangdong and the fifth-largest island in China.