The Southerner was a passenger express train in New Zealand's South Island between Christchurch and Invercargill along the South Island Main Trunk, that ran from 1970 to 2002. It was one of the premier passenger trains in New Zealand and its existence made Invercargill the southernmost passenger station in the world.

The South Island, also named Te Waipounamu in Māori, is the larger of the two major islands of New Zealand in surface area, the other being the smaller but more populous North Island. It is bordered to the north by Cook Strait, to the west by the Tasman Sea, and to the south and 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 altitude, it has an oceanic climate.