Zhoushan (help·info), formerly romanized as Chusan, is a prefecture-level "city"[b] in northeastern Zhejiang Province in eastern China. It consists of an archipelago of islands at the southern mouth of Hangzhou Bay, off Ningbo. The prefecture's city proper is Dinghai on Zhoushan Island, now administered as the prefecture's Dinghai District. During the 2010 census, Zhoushan Prefecture's population was 1,121,261, out of whom 842,989 lived in the urban districts of Dinghai and Putuo.