Time of day and time of year probably influence the result.
However, you can always go from POR to a theme park (e.g., AK - assuming that the park is open) and then from there to AKL. I've gone from YC/BC to AK and then from AK to AKL (for dinner at Boma a while back) and it wasn't too difficult.
The other option is to go from POR to DTD to AKL, but if the bus from DTD to AKL is anything like the ones from DTD to YC/BC, it might take a while.