Rockingham is a city and primary centre in Western Australia south-west of the Perth city centre and south of Fremantle. It has a beachside location at Mangles Bay, the southern extremity of Cockburn Sound. To its north stretches the maritime and resource-industry installations of Kwinana and Henderson. Offshore to the north-west is Australia's largest naval fleet and submarine base, Garden Island, connected to the mainland by an all-weather causeway.