Times in Ports due to tides & other port authority issues are unfortunate, but happen. we went to Kelly Tarltons Underwater World is worth the visit, 10 minutes from port, reasonable entree fee & lots to see. look at what to do before you leave Australia is a good suggestion.
Again as above with Port Authorities. We went to MataMata to see The Hobbiton Movie set again well worth the excursion beautiful country side, movie set great. Then to Rotarua to Skyline luge the view from Mt Ngongotaha was spectacular.