South Island or Te Waipounamu [Maori, = the waters of greenstone] (1996 pop. 900,114), 58,093 sq mi (150,461 sq km), New Zealand. It is the larger but less populous of the two principal islands of the country and is also known as the Mainland. It is separated from North Island, the other principal island, by Cook Strait and from Stewart Island by Foveaux Strait. The Clutha and Waitaki are the largest rivers. The island includes the extensive Canterbury Plains and the Southern Alps, which extend almost the entire length of the island. Fiordland National Park includes a major portion of the southwest. The South Island's principal cities are Christchurch, Dunedin, and Invercargill. The South Island is New Zealand's main source of native timber. Grain and fruit are grown and sheep are raised; some coal, gold, and oil is found there. The island has several large hydroelectric projects.