A true atoll, Palmerston Island consists of a number of sandy islets on a continuous ring of coral reef enclosing a lagoon. The largest of the islets include Palmerston, North Island, Lee To Us, Leicester, Primrose, Toms, and Cooks. The total land area of the islets is approximately 1 square mile (2.6 km2). The coral reef covers about 3,600 acres (15 km2). The lagoon is some 7 miles (11 km) across, covering an area of 56 square kilometres (22 sq mi). There are several small passages through the reef for boats, though there is no safe entry for large ships. At a latitude of 18 degrees south, Palmerston enjoys a tropical climate but is exposed to severe tropical cyclones. A particularly destructive series of storms occurred during the 1920s and 1930s.
All the islets are wooded with coconut palms, pandanus, and native trees. There is some natural ground water on Palmerston but water captured from rainfall is preferred for drinking. Shellfish inhabit the reef, and fish are abundant although there are concerns about overfishing. There are only 62 people living in Palmerston, all but three descended from an Englishman named William Marsters (see History, below).
The economy is based on fishing, tourism, copra, and bird feathers, though Palmerston’s extreme remoteness makes a cash market difficult to maintain; in fact it is more like the subsistence ways of life in the northern atolls. Electricity and other modern utilities are available on the island. A recently built telephone station provides the only permanent link to the outside world. The island has no airport or regular air service, but cargo ships visit a few times a year.
Palmerston was discovered by Captain Cook in 1774, but he did not land on the island until 13 April 1777. He found it uninhabited, though some ancient graves were discovered. Cook named the island after Henry Temple, 2nd Viscount Palmerston, then Lord of the Admiralty. The ancient name of the island was supposedly Avarau, meaning "two hundred harbour entrances". In 1863 William Marsters, a ship's carpenter and barrel maker, arrived on Palmerston from Manuae with two Polynesian wives and annexed the island from the British government. He added a third wife and sired a large family of some 23 children, whose descendants now inhabit Palmerston. Thus, Palmerston Island is the only island in the Cook Islands for which English is the native language.
William Masters, originally thought to have come from Leicestershire, England, is now thought to have come from Gloucestershire, which might explain why his descendants now spell the name "Marsters" due to the Gloucestershire accent. By the time his youngest daughter Titana Tangi died in 1973, there were over a thousand of Marsters' descendants living in Rarotonga and New Zealand.
Though only some 50 family members remain on Palmerston, all of Marsters' descendants consider the island their ancestral home. In 1954 the family was granted full ownership of the island. Three branches of the family remain on Palmerston, each branch being descended from one of William's three wives, marriage within a family group being prohibited. All of William's wives came from Tongareva and there are still many family links and common ancestors between these atolls.
Palmerston is administered by the Cook Islands government, through the Palmerston Island Administration (PIA), in association with New Zealand.
The Island's Council consists of six members, the three heads of each family and three other members appointed by each family. The Mayor is Bob Marsters.