; formerly transliterated as Chusan, is a prefecture-level city in northeastern Zhejiang province of Eastern China. One of the two prefecture-level cities of the People's Republic of China consisting solely of islands (the other is Sansha in Hainan, however its territory is in dispute), it lies across the mouth of the Hangzhou Bay, and is separated from the mainland by a narrow body of water. On 8 July 2011 the central government approved Zhoushan's as Zhoushan Archipelago New Area a state-level new area. At the 2010 census, its population was 1,121,261 whom 842,989 lived in the built-up area made of Dinghai and Putuo counties.