Take the ferry from Circular Quay to Watsons Bay. You can walk around the area which is a mix of old fishermans cottages & modern multi-million$ houses. Camp Cove is a nice harbour beach to visit close by & then you can take the walk to South Head for spectacular views back up the harbour to Sydney, across to North Head & out to sea. From Watsons Bay you could also catch a bus or taxi to Bondi Beach, only a few kilometers away.