I took a very expensive scenic cruise which fortunately also delivered me across the Cook Straight! The Interislander ferry takes about 3 hours, the 1st hour of which is through the beautiful Marlborough Sounds. The next hour is across the Straight itself which was fortunately pretty calm for me! The final hour is coming into Wellington harbour which is again pretty scenic. I didn't stay in Wellington long - not really a city fan! I headed up the coast and found myself a nice beach-side car-park for the night!