Bluff is the very southern most tip of New Zealand, just 15 miles or so away from "The Third Island", Stewart Island.
Tisa and I actually tried to go to Stewart Island, first by boat, and then by plane, but we couldn't manage to secure a proper time slot that would get us there and back.
I would have to say that was one of very few disappointments on our entire trip, the fact that we never did make it to Stewart Island.