Semaphore South is a beachside suburb of Adelaide, in the City of Port Adelaide Enfield. The Semaphore South Post Office opened on 3 November 1947 and closed in 1978. Semaphore South is located in the state electoral district of Lee and the federal division of Hindmarsh. Le Fevre High School, originally spelt LeFevre, is located in the suburb, and is the oldest secondary school in the area. Although the site has earlier origins as a school, it was officially gazetted in 1910.