Weizhou Island (simplified Chinese: 涠洲岛; traditional Chinese: 潿洲島; pinyin: Wéizhōu Dǎo) is a Chinese island in Beibu Gulf in the Gulf of Tonkin. The largest island of Guangxi Zhuang Autonomous Region, Weizhou is west of Leizhou Peninsula, south of Beihai, and east of Vietnam. Administratively, it is part of Weizhou Town, Haicheng District of Beihai City. The name derives from Chinese 潿 wéi ("still water") and 洲 zhōu ("river islet").