The Cook Islands is a nation in the South Pacific, with political links to New Zealand. Its 15 islands are scattered over a vast area. The largest island, Rarotonga, is home to rugged mountains and Avarua, the national capital. To the north, Aitutaki Island has a vast lagoon encircled by coral reefs and small, sandy islets. The country is renowned for its many snorkeling and scuba-diving sites.