It is part of the archipelago of Tristan da Cunha which is part of the overseas territory of the United Kingdom known as Saint Helena, Ascension and Tristan da Cunha. Along with Gough Island, Inaccessible Island is a protected wildlife reserve and both make up the UNESCO World Heritage Site of Gough and Inaccessible Islands.
The island sits approximately 17 nautical miles to the southwest of the main island of the Tristan da Cunha archipelago. Mostly desolate and inhospitable, the island has one small landing site named Port David on the northwesternmost point.
Inaccessible Island was discovered in January 1656 during a voyage by 't Nachtglas ("the night glass"), a Dutch ship under the command of Jan Jacobszoon, 146 years after Tristan da Cunha was first sighted by Portuguese sailors. Jacobszoon originally named it "Nachtglas" island.
There are two explanations for the name "Inaccessible" island. One is that on maps the newly found island was referred to as "inaccessible" because the Dutch crew who landed were not able to reach its interior. The other claims that French captain d'Etcheverry renamed the island in 1778 after not being able to land. In 1803, US sealers led by Amasa Delano made landfall on the island.
The Stoltenhoff brothers, who arrived on Inaccessible from Germany in 1871, lived there for several years intending to make a living sealing and selling their wares to passing traders (forgetting how infrequently Inaccessible had visitors). However, due to the scarcity of food, they were "overjoyed" to be rescued in 1873 during HMS Challenger's visit to examine the flora and fauna there. The South African author Eric Rosenthal chronicled the Stoltenhoffs' adventure in 1952. The nearby Stoltenhoff Island is named after the brothers.
In 1922, the Shackleton–Rowett Expedition's ship, the Quest, stopped by Inaccessible briefly, and on-board naturalist Hubert Wilkins discovered a bird later named (after him) the Wilkins bunting (Nesospiza wilkinsi).
In 1938, the Norwegian Scientific Expedition spent three weeks on the island, during which time they managed to gain access to the plateau and extensively catalogued plants, birds, and rocks.
Another attempt at mapping the island was made during the Royal Society's expedition of 1962 to Tristan da Cunha, which took scientists to Inaccessible Island. Like many other explorers before them, the scientists were not able to reach the interior of the island.
Inaccessible Island was declared a nature reserve under the Tristan da Cunha Conservation Ordinance of 1976. Tristan islanders, however, were still permitted to harvest seabirds from the island.
In a 1982 expedition (October 16, 1982 – February 10, 1983), students and faculty of Denstone College in England made detailed maps of the island, studied its flora, fauna, and geology, and carried out a marking programme on more than 3,000 birds.
In 1997, Inaccessible Island's territorial waters out to 22 km (12 nmi) were declared a nature reserve under the Tristan da Cunha Conservation Ordinance of 1976. Currently, only guides from Tristan are allowed to take visiting cruise ships to Inaccessible; indeed, most trips to the island are now made at the request of expatriates.
In 2004 Inaccessible Island was added to the UNESCO World Heritage Site of Gough Island to create a new site of Gough and Inaccessible Islands.
It has frequently been noted on lists of unusual place names.
At least three confirmed shipwrecks have occurred off the coast of Inaccessible Island.
The first, and most dramatic, was that of Blenden Hall, a British ship which set sail in 1821 with 54 passengers and crew aboard with destination Bombay. Captain Alexander Grieg intended to sail past Saint Helena, but adverse currents carried her to Tristan da Cunha. She got caught in seaweed and on 22 July drifted aground on Inaccessible Island. All but two of those aboard survived the shipwreck. They spent the next four months subsisting on wild celery, seals, penguins, and albatross. They managed to build a boat some months later. The first attempt to sail to Tristan failed, resulting in the loss of six people; but the second attempt alerted the Tristanians to their plight. The remainder were then brought to Tristan, where the brig Nerina arrived about two months later and took most to Cape Town, South Africa.
The other two shipwrecks are the wreck of Shakespeare at Pig Beach in 1883, and Helen S Lea at North Point in 1897.
When Corporal William Glass and his family became the first settlers at Tristan da Cunha in 1816, goats and pigs were brought to Inaccessible Island to serve as a source of food. Some domestic animals remained for at least 57 years and helped to keep the Stoltenhoff brothers alive during their expedition, but they have now died out. Cattle, sheep, and dogs were also introduced to the island at various points in the island's history, but none remain.
No land mammals, reptiles, amphibians, butterflies, or snails have recently been found at Inaccessible. The island does have 64 native plant species, including 20 types of flowering plants and 17 species of ferns. In addition, 48 invertebrate species exist on the island, 10 of which were introduced. Subantarctic fur seals and southern elephant seals have also been seen at the island in increasing numbers, and cetaceans live in the surrounding waters most notably southern right whales and resident population of dusky dolphins.
Inaccessible is perhaps best known for the Inaccessible rail, the world's smallest living flightless bird. The island has been identified as an Important Bird Area (IBA) by BirdLife International as a breeding site for seabirds and its endemic landbirds. Birds for which the IBA is significant include northern rockhopper penguins (up to 27,000 breeding pairs), Tristan albatrosses (2-3 pairs), sooty albatrosses (200 pairs), Atlantic yellow-nosed albatrosses (1100 pairs), broad-billed prions (up to 500,000 pairs), soft-plumaged petrels (up to 50,000 pairs), spectacled petrels, great shearwaters (up to 2 million pairs), little shearwaters (up to 50,000 pairs), white-faced storm petrels (up to 50,000 pairs), white-bellied storm petrels (up to 50,000 pairs), Antarctic terns, Inaccessible rails (up to 5000 pairs), Tristan thrushes and Inaccessible buntings.
Inaccessible Island has been used by the islanders of Tristan da Cunha for several economic purposes. The island has guano deposits and eggs, but due to the difficulty of traveling about the island, the islanders have generally chosen to go to Nightingale Island instead.