Fremantle (frēˈmănˌtəl, frĭmˈəntəl) [key], city (1996 pop. 24,276), Western Australia, SW Australia, a suburb of Perth, on the Indian Ocean at the mouth of the Swan River. It is the terminus of the Trans-Australian RR and the chief commercial port of the state. The chief exports are wheat, wool, fruit, and flour; oil, steel, and phosphates are imported. The 1987 America 's Cup challenge was held here.