Time Out says
The largest island in Sydney's harbour and set at the junction of the Parramatta and Lane Cove rivers, Cockatoo Island is 18 hectares in size and named for the presence of sulphur-crested cockatoos. Before 1839, when a prison was built to house convicts from Norfolk Island, it was covered with red gums and was almost certainly an Aboriginal fishing spot.
The convicts eventually relocated to Darlinghurst Gaol and the island had a brief stint hosting an industrial school for girls and a naval training ship for boys (but due to ‘unseemly and unscheduled meetings' the girls moved to Parramatta). However, the island was mostly used for shipbuilding and repairs; its several docks serviced the Royal Navy during WWII and was the construction site of Australia's first steel warship. The island's maritime industrial activity ceased in 1992, and Cockatoo Island only opened to the public in 2007.
Today, the island is run by the Sydney Harbour Federation Trust and remains commercial free, although there are talks of reintroducing boat building on a smaller scale. The trust run different types of tours – visitors can opt for a self-guided audio tour (90 mins; $5-$8), on-demand guided tour (60 or 90 mins; $16) or a pensioner tour (60 or 90 mins; $12). Those who want to stay on a bit longer also have options – there are camp sites, glamping packages, apartments or heritage holiday houses.
Mon-Fri 6.15am-11.37pm; Sat-Sun 6.45am-11.37pm. Camping: (02 8898 9774). $45 per site, $75 per site with tent, sleeping mat, chair & lantern hire.