COOK ISLANDS

Cook Islands, self-governing island state in free association with New Zealand, located in the South Pacific Ocean. Its 15 small atolls and islands have a total land area comparable to that of a medium-sized city, but they are spread over about 770,000 square miles (2,000,000 square km) of sea—an area nearly as large as Greenland. Niue, the westernmost of the islands, is an administratively separate state. The administrative seat is Avarua, on the island of Rarotonga. Area (land only) 91.4 square miles (236.7 square km). Pop. (2011) 14,974.

Each island is the top of one or more volcanoes, but only on the largest islands do the plugs and craters of now-extinct volcanoes still dominate the skyline; the highest of these rises to 2,139 feet (652 metres) at Te Manga, on Rarotonga, an island only 4 miles (6 km) wide. Many of the other islands of the southern group (Aitutaki, Atiu, Mangaia, Manuae, Mauke, Mitiaro, Palmerston, and Takutea) show various combinations of atoll and high-island formation. In the northern group (Manihiki, Nassau, Penrhyn, Pukapuka, Rakahanga, and Suwarrow), all except Nassau are atolls, narrow and low-lying sandbanks resting on circular reefs around lagoons rich in marine life.

Because the land areas are so small, there are no rivers, and only the largest islands have even small streams. There are small freshwater lakes on the high islands of Mangaia, Atiu, and Mitiaro; saltwater lagoons inside all the atolls; and fringing lagoons between most islands and their outer reefs. The rain that falls on the atolls permeates the island coral and is naturally stored in a lens-shaped layer above the heavier salt water. The islanders must rely on wells and rainwater storage tanks to conserve their limited sources of water.

All the islands lie within the tropics, though the southernmost just barely so. Because the Cook Islands are small, mid-ocean islands swept by the southeast trade winds, temperatures are generally moderate. Mean annual temperatures on the southern island of Rarotonga are in the mid-70s F (about 24 °C), but on the northernmost island of Penrhyn they are in the low 80s F (about 28 °C).

Seasons are not clearly differentiated. The English terms summer, winter, spring, and autumn are used, but Cook Islanders also recognize the traditional local patterns of prevailing winds, rainfall, and temperature. Precipitation, though erratic over the years, tends to be uniform across the various islands. It averages about 80 inches (2,000 mm) on Rarotonga, though with considerable difference between the windward and leeward sides of the central mountains; precipitation is slightly lower on Aitutaki and slightly higher on Penrhyn.

A spectacular climatic hazard is the occurrence of tropical cyclones (locally called typhoons), which strike with destructive force between December and March about once or twice every 10 years. Less spectacular but at times equally destructive of agriculture are droughts, to which the northern group of islands is more vulnerable than the southern.

Only a limited range of plant life thrives in the north, with coconuts and pandanus being predominant. On the fertile areas of the southern islands, a wide range of tropical fruits and vegetables flourishes. Indigenous species include taro, yams, bananas, breadfruit, and sweet potatoes. Introduced species—in many cases grown for export—include citrus fruits, tomatoes, pineapples, papayas, beans, and zucchini.