And the sea is an integral part of both areas. However there the similarity ends. The world's highest sea cliff is to be found in Milford Sound. The Fiords themselves are often 200 metres deep only a few metres from shore. The vegetation is very dense as Fiordland is true rain forest with an annual rainfall measured in tens of metres rather than centimetres.
Nothofagus species are the dominant large trees.
Stewart Island on the other hand is lower and more rounded. Although subject to past glaciation the many bays are drowned river valleys rather than the result of deep glaciation. The bays are relatively shallow and the forest is devoid of beech trees. In the south particularly the climate is reflected in low stunted scrub instead of high forest and large areas of granite devoid of all but the most hardy low growing plants and lichens. Both areas are home to a large variety of pelagic, shore and land birds.