Macquarie Island is an island in the southwestern Pacific Ocean, about halfway between New Zealand and Antarctica.
The flora has taxonomic affinities with other subantarctic islands, especially those south of New Zealand. Plants rarely grow over 1 m in height, though the tussock-forming grass Poa foliosa can grow up to 2 m tall in sheltered areas. There are over 45 vascular plant species and more than 90 moss species, as well as many liverworts and lichens. Woody plants are absent.
The island has five principal vegetation formations: grassland, herbfield, fen, bog and feldmark. Bog communities include 'featherbed', a deep and spongy peat bog vegetated by grasses and low herbs, with patches of free water. Endemic flora include the cushion plant Azorella macquariensis, the grass Puccinellia macquariensis, and two orchids – Nematoceras dienemum and Nematoceras sulcatum.
Mammals found on the island include subantarctic fur seals, Antarctic fur seals, New Zealand fur seals and southern elephant seals – over 80,000 individuals of this species. Diversities and distributions of cetaceans are less known; southern right whales and orcas are more common followed by other migratory baleen and toothed whales, especially sperm and beaked whales, which prefer deep waters. So-called 'Upland Seals' once found on Antipodes Islands and Macquarie Island have been claimed by some researchers as a distinct subspecies of fur seals with thicker furs, although it is unclear whether these seals were genetically distinct.
Royal penguins and Macquarie shags are endemic breeders, while king penguins, southern rockhopper penguins and gentoo penguins also breed here in large numbers. The island has been identified by BirdLife International as an Important Bird Area because it supports about 3.5 million breeding seabirds of 13 species.