The South Island is the largest of the three major islands of New Zealand in surface area, the other being the smaller but more populous North Island and sparsely populated Stewart Island. It is bordered to the north by Cook Strait, to the west by the Tasman Sea, to the south by the Foveaux Strait and Southern Ocean, and to the east by the Pacific Ocean. The South Island covers 150,437 square kilometres (58,084 sq mi), making it the world's 12th-largest island, constituting 56% of New Zealand's land area. At low altitudes, it has an oceanic climate. The major centres are Christchurch, with a metropolitan population of 521,881, and the smaller Dunedin. The economy relies on agriculture, fishing, tourism, and general manufacturing and services.