The Tiwai Island camp is the practical centre of a visit: a simple cluster of accommodation, guide arrangements, and boat access set inside the rainforest. It is not luxurious, and that is part of the point. You sleep close enough to the forest to hear the island after dark.
Use the camp to organise guided walks and canoe trips rather than trying to wander independently. The island is small, but the forest is dense, wildlife is easier to see with local eyes, and visitor fees help fund conservation and community projects in the surrounding villages.