Semaphore Park is a suburb in the Australian state of South Australia located in the west of Adelaide on the coastline of Gulf St Vincent. The northern end of the suburb is considered to be located within the Lefevre Peninsula. Semaphore Park originally started as a private sub-division in Section 64 in the cadastral unit of the Hundred of Yatala under the names of New Liverpool and Mellor Park. Boundaries were created for the suburb on 30 September 1976.