Ecologically, the Auckland Islands form part of the Antipodes Subantarctic Islands tundra ecoregion. Along with other New Zealand Sub-Antarctic Islands, they were designated a UNESCO World Heritage Site in 1998.
The Auckland Islands lie 360 kilometres (220 mi) south of Stewart Island, and 465 kilometres (290 mi) from the South Island port of Bluff, between the latitudes 50° 30' and 50° 55' S and longitudes 165° 50' and 166° 20' E.
They include Auckland Island, Adams Island, Enderby Island, Disappointment Island, Ewing Island, Rose Island, Dundas Island and Green Island, with a combined area of 625 square kilometres (240 sq mi). The islands are close to each other, separated by narrow channels, and the coastline is rugged, with numerous deep inlets.
Auckland Island, the main island, has an approximate land area of 510 km2 (197 sq mi), and a length of 42 km (26 mi). It is notable for its steep cliffs and rugged terrain, which rises to over 600 m (1,969 ft). Prominent peaks include Cavern Peak (659 m or 2,162 ft), Mount Raynal (635 m or 2,083 ft), Mount D'Urville (630 m or 2,067 ft), Mount Easton (610 m or 2,001 ft), and the Tower of Babel (550 m or 1,804 ft). The southern end of the island broadens to a width of 26 km (16 mi).
Here, the narrow channel of Carnley Harbour (the Adams Straits on some maps) separates the main island from the roughly triangular Adams Island (area approximately 100 km2 or 39 sq mi), which is even more mountainous, reaching a height of 705 m (2,313 ft) at Mount Dick. The channel is the remains of the crater of an extinct volcano, and Adams Island and the southern part of the main island form the crater rim. The main island features many sharply incised inlets, notably Port Ross at the northern end.
The group includes numerous other smaller islands, notably Disappointment Island (10 km or 6.2 mi northwest of the main island) and Enderby Island (1 km or 0.62 mi off the northern tip of the main island), each covering less than 5 km2 (2 sq mi).
Most of the islands have a volcanic origin, with the archipelago dominated by two 12 million year old Miocene volcanoes, subsequently eroded and dissected. These rest on older volcanic rocks 15-25 million years old with some older granites and fossil-bearing sedimentary rocks from around 100 million years ago.
The archipelago features a subpolar oceanic climate (Cfc according to the Köppen climate classification system). The Auckland Islands have a fairly constant cool & mild weather year-round, with neither winter being excessively cold nor summer excessively hot.
Evidence exists that Polynesian voyagers first discovered the Auckland Islands. Traces of Polynesian settlement, possibly dating to the 13th century, have been found by archaeologists on Enderby Island. This is the most southerly settlement by Polynesians yet known.
A whaling vessel, Ocean, discovered the islands in 1806, finding them uninhabited. Captain Abraham Bristow named them "Lord Auckland's" on 18 August 1806 in honour of his father's friend William Eden, 1st Baron Auckland. Bristow worked for the businessman Samuel Enderby, the namesake of Enderby Island. The following year Bristow returned on the Sarah in order to claim the archipelago for Britain. The explorers Dumont D'Urville in 1839, and James Clark Ross visited in 1839 and in 1840 respectively.
Whalers and sealers set up temporary bases, the islands becoming one of the principal sealing stations in the Pacific in the years immediately after their discovery. By 1812 so many seals had been killed that the islands lost their commercial importance and sealers redirected their efforts towards Campbell and Macquarie Islands. Visits to the islands declined, although recovering seal populations allowed a modest revival in sealing in the mid-1820s.
Now uninhabited, the islands saw unsuccessful settlements in the mid-19th century. In 1842 a small party of Māori and their Moriori slaves from the Chatham Islands migrated to the archipelago, surviving for some 20 years on sealing and flax growing. Samuel Enderby's grandson, Charles Enderby, proposed a community based on agriculture and whaling in 1846. This settlement, established at Port Ross in 1849 and named Hardwicke, lasted only two and a half years.
The Auckland Islands were part of the Colony of New Zealand under the Letters Patent of April 1842 which fixed the southern boundary of New Zealand at 53° south, but they were then excluded by the Act of 1846 which defined the southern boundary at 47° 10' south; however they were again included by the New Zealand Boundaries Act of 1863, an act of the Imperial Parliament at Westminster which extended the boundaries of the colony once more.
The rocky coasts of the islands have proved disastrous for several ships. The Grafton, captained by Thomas Musgrave, was wrecked in Carnley Harbour in 1864. Madelene Ferguson Allen's narrative about her great-grandfather, Robert Holding, and the wreck of the Scottish sailing ship the Invercauld, wrecked in the Auckland Islands a few months later in 1864, counterpoints the Grafton story. François Édouard Raynal wrote also Les Naufragés, ou Vingt mois sur un récif des îles Auckland.
In 1866 one of New Zealand's most famous shipwrecks, that of the General Grant, occurred on the western coast. Fifteen survivors waited for rescue on Auckland Island for eighteen months. Several attempts have failed to salvage its cargo, allegedly including bullion.
Because of the probability of wrecks around the islands, calls arose for the establishment of emergency depots for castaways in 1868. The New Zealand authorities established and maintained three such depots, at Port Ross, Norman Inlet and Carnley Harbour from 1887. They also cached additional supplies, including boats (to help reach the depots) and 40 finger-posts (which had smaller amounts of supplies), around the islands. When a further maritime tragedy occurred in 1907, with the loss of the Dundonald and 12 crew off Disappointment Island, the shipwreck's fifteen survivors lived off the supplies in the Auckland Island depot.
The 1907 Sub-Antarctic Islands Scientific Expedition spent ten days on the islands conducting a magnetic survey and taking botanical, zoological and geological specimens.
From 1941 to 1945 the islands hosted a New Zealand meteorological station as part of a coastwatching programme staffed by scientist volunteers and known for security reasons as the "Cape Expedition". The staff included Robert Falla, later an eminent New Zealand scientist. Currently the islands have no inhabitants, although scientists visit regularly and the authorities allow limited tourism on Enderby Island and Auckland Island.
New reserves including Auckland Islands were established in 2014, which are about 15 times larger than the reserve on Stewart Island, making Subantarctic islands the largest natural sanctuary in the nation.
The botany of the islands was first described in the Flora of Lord Auckland and Campbell's Islands, a product of the Ross expedition of 1839–43, written by Joseph Dalton Hooker and published by Reeve Brothers in London between 1843 and 1845.
The vegetation of the islands sub-divides into distinct altitudinal zones. Inland from the salt-spray zone, the fringes of the islands predominantly feature forests of southern rata Metrosideros umbellata, and in places the subantarctic tree daisy (Olearia lyallii), probably introduced by sealers. Above this exists a subalpine shrub zone dominated by Dracophyllum, Coprosma and Myrsine (with some rata). At higher elevations tussock grass and megaherb communities dominate the flora.
The islands host the largest communities of subantarctic invertebrates, with 24 species of spider, 11 species of springtail and over 200 insects. These include 57 species of beetle, 110 flies and 39 moths. The islands also boast an endemic genus and species of weta, Dendroplectron cryptacanthus.
The freshwater environments of the islands host a freshwater fish, the koaro or climbing galaxias, which lives in saltwater as a juvenile but which returns to the rivers as an adult. The islands have 19 species of endemic freshwater invertebrates, including one mollusc, one crustacean, a mayfly, 12 flies and two caddis flies. Auckland Islands cockle are endemic to the islands.
Only two native mammals exist: two species of seal which haul out on the islands, the New Zealand fur seal and the threatened New Zealand sea lion. Southern elephant seals started to re-colonize on the islands, too.
A well-recovering population in excess of 2,000 southern right whales is found off the islands, and Port Ross area is considered to be the most important and well-established congregating ground for whales in New Zealand waters. Its importance exceeds the Campbell Island ground.
The islands hold important seabird breeding colonies, among them albatrosses, penguins and several small petrels, with a million pairs of sooty shearwater. Landbirds include red-fronted and yellow-crowned parakeet, New Zealand falcon, tui, bellbirds, pipits and an endemic subspecies of tomtit.
The whole Auckland Island group has been identified as an Important Bird Area (IBA) by BirdLife International because of its significance as a breeding site for several species of seabirds as well as the endemic Auckland shag, Auckland teal, Auckland rail, and Auckland snipe. The seabirds include southern rockhopper and yellow-eyed penguins; Antipodean, southern royal, light-mantled and white-capped albatrosses; and white-chinned petrel.
Several introduced species have come to the islands; goats, other useful animals and seed were brought to the islands by Captains Musgrave and Norman 1865, returning to search for castaways; ecologists eliminated or allowed to go extinct cattle, sheep, goats, dogs, possums and rabbits in the 1990s, but feral cats, pigs and mice remain on Auckland Island. The last rabbits on Enderby Island were removed in 1993 through the application of poison, also eradicating mice there.
Curiously, rats have never managed to colonise the islands, in spite of numerous visits and shipwrecks and their ubiquity on other islands. Introduced species affected the native vegetation and bird life, and caused the extinction of the New Zealand merganser, a duck formerly widespread in southern New Zealand, and ultimately confined to the islands.