Shark Island is an island in Sydney Harbour, Australia. It lies offshore of the Sydney suburbs of Point Piper, Rose Bay and Vaucluse, in the eastern section of the harbour between the Harbour Bridge and the harbour entrance. The island derives its name from its apparent shape, which is claimed to resemble that of a shark. The island measures some 250 metres by 100 metres, and was once used as a quarantine station for animals. Today it is uninhabited, and forms part of the Sydney Harbour National Park. Source: [wikipedia: shark island, port jackson]