Changdao County (simplified Chinese: 长岛县; traditional Chinese: 長島縣; pinyin: Chángdǎo Xiàn; lit. 'Long Island County') was a county in Yantai, a prefectural area of Shandong in the People's Republic of China. It consisted of the Changshan Islands within the Bohai Strait, directly north of Penglai. They are known for their sandy beaches and picturesque limestone cliffs. The total land area measured 56 square kilometers (22 sq mi) and the coastline 146 km (91 mi). The population in 2020 was 40,898. In 2020, Changdao County was merged into the county-level city of Penglai and became Penglai District.