The Cockatoo Island Dockyard was a major dockyard in Sydney, Australia, based on Cockatoo Island. The dockyard was established in 1857 to maintain Royal Navy warships. It later built and repaired military and battle ships, and played a key role in sustaining the Royal Australian Navy. The dockyard was closed in 1991, and its remnants are heritage listed as the Cockatoo Island Industrial Conservation Area.