Buller River, river in northwestern South Island, New Zealand. Named after Charles Buller, founder of the New Zealand Company, it is the major river of the island’s west coast. Rising as the Travers River on the St. Arnaud Range of the central highlands, it drains Lakes Rotoiti and Rotoroa, flows west for 110 miles (177 km), and enters the Tasman Sea at Westport. The Buller River receives the outflow from a 2,510-square-mile (6,500-square-kilometre) basin and may have a flood level discharge as great as 437,000 cubic feet (12,400 cubic m) per second. It flows through a generally mountainous region but crosses gravel plains at Murchison, Inangahua, and the coast. The river’s gorge, which is most scenic at Inangahua Junction, is an important tourist attraction. Other economic activities of the Buller River valley include coal mining, centred on Westport, and dairying. The river is a transportation focus: roads and rail lines to Canterbury (southeast) parallel the river from its mouth to Inangahua, the road from Westport to Nelson (north) ascends as far as Kawatiri, and the road to Blenheim (northeast) follows the river’s valley up beyond the headwaters.