There's the Bluebridge ferry which will take us across Cook Strait to the South Island.
The Bluebridge ferry departs at 3.00 am and 1.00 pm. We pay 288 $: 190 $ for the vehicle (price is calculated over vehicle length and height, ours is 6,60 m long, but although we tell them they just charge 6,50 m) + 49 $ per person.
Read more about Wellington in the travelogue: