Changhai County (simplified Chinese: 长海县; traditional Chinese: 長海縣; pinyin: Chánghǎi Xiàn; literally: "long sea") is under the administration of Dalian, Liaoning province, People's Republic of China. It consists of several islands in the Yellow Sea and is located offshore of the Liaodong Peninsula. There are 112 small islands and reefs in the county, traditionally called the Outer Chang Mountains Island Chain. Its area is 156.89 square kilometres (60.58 sq mi) and its permanent population as of 2010 is 77,951, making it Dalian's least populous county-level division, and the county government is located in the Dongshan neighborhood of the town of Dachangshandao.
There are 2 towns and 3 township in the county.
Xiaoshuikou (小水口) in Xiaochangshan Island, Changhai County