The Twins, located about 3km west of the north west point of Carcass Island, have been a Falklands Conservation Nature Reserve since 1984 when they were leased from the Royal Society for Nature Conservation. The freehold was acquired in 1993. They comprise two islands: South Twin and North Twin and are legally designated as a Wild Animal and Bird Sanctuary.
The Twins are good examples of low lying, tussac-covered islands that have not been grazed by herbivores or invaded by alien predatory mammals.
Their status as Nature Reserves owned by Falklands Conservation will ensure that they remain in their present natural condition.
North Twin (8ha) is about 600m long and generally less than 100m in width. There is a wide rocky reef at the southwestern point which is exposed at low tide. A narrow reef extends along the western coast with a boulder beach on which dead kelp and a few bleached, drifted tree trunks have become stranded. The Island barely reaches 5m (about 16 feet) at a few small rocky points.
South Twin is about 1km long and about 250m across at its widest point. Around the northern point a wide fringe of shelf rock is exposed at low tide. The Island is generally very low lying, the highest point being only 8m (25 feet) above sea level. There are sand dunes behind a noticeable white sand beach on the northeastern side and some low rocky points. A large accumulation of dead, rotting kelp was found to the north of the southeastern point along a narrow boulder beach.