Great place to visit. Fortunately, we spent 3 day prior to boarding the cruise to explore the city. Trips to Watson Bay and Manly are recommended. From Watson bay there is a nice walk to the lighthouse and back and you can then take bus to Bondi beach.
Unfortunately, we did not have enough time in Darwin. The town is quite small and there not too much to do there. However within 90 minutes drive you have a national park to explore but with a half day it is impossible to manage. Therefore left to explore the town and also the Botanical gardens which are worth seeing.
A little disappointing but that was due to the weather. Enjoyed walking around the markets and also Hollywood road with all its antique shops. Hong Kong looked great at night though and it well worth staying out to explore and see the lights.