The Southern Islands is a planning area consisting of a collection of islets located within the Central Region of Singapore, once home to the native Malay islanders and sea nomads before they were relocated to the mainland for urban redevelopment and future use. The islands that form the planning area are Kusu Island, Lazarus Island, Pulau Seringat, Pulau Tekukor, Saint John's Island, Sentosa and the two Sisters' Islands. The islands encompass a total land area of about 5.58 square kilometres. The Sentosa Development Corporation oversaw the development and maintenance of these offshore islands south of Singapore from 1976 to March 2017, when it handed it back to the Singapore Land Authority.
Southern Islands planning area is situated on the Singapore Straits, south of the mainland planning area of Bukit Merah. It also shares maritime boundary with the Western Islands planning area.