Getting to Queen Charlotte Walk from Wellington is half the fun. Queen Charlotte is located in convoluted Marlborough Sounds, with numerous coves, bays, and islands that offer up an interesting vista, as well as protected areas where many can kayak. We took the interisland ferry from Wellington, which takes about 3 hours, and is totally worthwhile.
As you set out on the interislander ferry, be sure to stand at the rear of the ferry to admire the Wellington skyline. Once on open water, the passage is a bit ordinary, until you get to Marlborough Sounds. The many islands and bays of Marlborough requires that the ferry weaves in and out, while the fog and mist mean that once in a while, suddenly, an island that has heretofore been covered by the fog will appear as if out of nowhere. To enjoy the crossing, make sure that one of the crossings is one the morning.
In the evening, the last ferry ride is typically on the newest ferry, which of course takes cars as well as passengers. This ferry is really something else. It is huge, with space for a home theatre, a couple of bars, open spaces where large comfortable leather chairs and couches are set out for passengers who need to sleep or just rest, and I believe even casinos, although don't hold me to it if you don't find one. On my trip, they showed the "Truman Show" to a packed audience. The sound system was superb, and it was just like sitting in a theatre. It is like being on a small cruise. I was totally impressed--the ferry experience in itself is worth crossing the water.