Keppel Island is one of the Falkland Islands, lying between Saunders and Pebble islands, and near Golding Island to the north of West Falkland on Keppel Sound. It has an area of and its highest point, Mt. Keppel, is high. There is a wide, flat valley in the centre of the island with several freshwater lakes. The central valley rises steeply to the south-west, west and north. The north-east is low-lying, with a deeply indented coastline. The large population of Norway rats on the island constitute an invasive species. They are predators of birds that nest there, of which several species are of conservation interest.
The mission on Keppel Island was established in 1855 by the South American Missionary Society, initially under Captain William Parker Snow. It operated until 1898. Captain Allen Gardiner, founder of the Society, had proposed use of this island, as a less hostile climate and environment than Tierra del Fuego, from which missionaries could gain the confidence of the Yaghan and learn their language. From 1856, Anglican missionaries persuaded several Yaghan to move from Tierra del Fuego to Keppel Island, where they learnt farming techniques and some English. The Yahgan did not go to Keppel Island until a few years after the British built "Cranmer Station" near Committee Bay. One of the more notable visitors to Cranmer Station was Jemmy Button, a Yahgan who had learnt English and was taken to England as a visitor with two other Yahgans aboard in 1830–31, on its first return trip. After some setbacks, the mission succeeded in 1869 in founding another mission on Tierra del Fuego, at Ushuaia near the Beagle Canal, under the leadership of Waite Stirling, who later became a bishop in the region. Thomas Bridges was a young Anglican missionary who started there in 1871, having already learned the Yahgan language while on Keppel Island. He became fluent, and over a decade, wrote a Yámana grammar and dictionary containing 30,000 words. It was considered valuable for ethnological study of the people. Today, the mission bailiff's house, the chapel, and the stone walls of some of the Yaghan dwellings remain intact on Keppel Island. Some stone walls have been used to provide foundations for present-day buildings. The ruins are listed buildings and represent amongst the oldest in the islands.