It is bordered to the north by Cook Strait, to the west by the Tasman Sea, to the south and east by the Pacific Ocean.
The territory of the South Island covers 151,215 square kilometres (58,384 sq mi) and is influenced by a temperate climate.
The South Island is sometimes called the "Mainland". While it has a 33% larger landmass than the North Island, only 24% of New Zealand's 4.4 million inhabitants live in the South Island.
In the early stages of European (Pākehā) settlement of the country, the South Island had the majority of the European population and wealth due to the 1860s gold rushes. The North Island population overtook the South in the early 20th century, with 56% of the population living in the North in 1911, and the drift north of people and businesses continued throughout the century.