Take a walk to the surrounding city areas, go to the aquarium, maritime museum, or just walk along the boardwalks at Darling Harbour. Visit the historic district of The Rocks. Walk up to Chinatown in the city south for Yum Cha.
Take a ferry trip from Circular Quay to the Harbour Islands, Manly or Parramatta.
Walk, or catch the train, over the harbour bridge to the Lower North Shore.