Some of the most fertile land in the southwestern North Island of New Zealand is on the floodplains of the Manawatu and Rangitikei Rivers, in an area known as the Manawatu Plains. Stretching from the northern Horowhenua around Levin in the south to Marton in the north, this great triangular area of low-lying land extends inland from the South Taranaki Bight almost as far as Ashhurst at the mouth of the Manawatu Gorge, and covers an area of around 1,000 square kilometres (390 sq mi).