The principal river on the West Coast flows swift and broad from Lake Rotoiti (in Nelson Lakes National Park) westward through uplifted mountain blocks to reach the sea at Westport. For most of its 169 kilometres the river is contained within gorges, steep-sided and well-bushed, engendering much remarkable scenery, particularly in the Lower Buller Gorge. Between them Highways 6 and 63 follow the river for most of its length.
The changing light playing on densely forested ranges is a constant diversion. There are numerous picnic places and lookout points to remind of the havoc wrought by earthquakes in 1929 and 1968, whose tremors destabilised much of the land.
The river is named after Charles Buller, a director of the New Zealand Company. It has been suggested that the title was chosen in London, at a board meeting, but research has shown that the explorers Brunner, Heaphy and Fox seriously debated the merits of several names before deciding to honour the brilliant young British parliamentarian. There are several versions of the Maori name, usually given as Kawatiri or Kawatere and freely translated as „water flowing swiftly through a rocky gorge“.