largest island in the southern group of the Cook Islands, in the South Pacific Ocean, about 2,100 miles (3,400 km) northeast of New Zealand. Volcanic in origin, it has a rugged interior rising to 2,139 feet (652 metres) at Te Manga. Surrounding its mountainous core is a plain, an ancient raised fringing coral reef covered with sediment. The island itself is fringed by a coral reef.

Visited in 1789 by mutineers from the British ship HMS Bounty, Rarotonga bears marks of a long period of habitation, including marae, or temple platforms, in the valley traversed by Tupapa Stream. The Ara Metua, an ancient pathway, circles the island inland from a paved coastal road. Rarotonga was the base from which John Williams of the London Missionary Society (who arrived in 1823) sought to Christianize the islands.

Avarua is the seat of administration for the Cook Islands and the location of a major port. Absence of a suitable lagoon once forced oceangoing ships to lie off the reef and move cargoes ashore via lighters. However, the harbour at Avatiu, to the west of Avarua, has been dredged, and sizable vessels now tie up at the wharf there. Rarotonga is the entry point for the Cook Islands by air. Rarotonga's economy is based on citrus fruits, pineapples, coconuts, bananas, and light industry. The tourist industry has become a major component of the economy since the introduction of international air service in 1973. The island has a hospital, Tereora College (a secondary school), and a teacher-training college at Nikao. Area 25.9 square miles (67.1 square km). Pop. (2006 prelim.) 14,153.