The Ashburton River / Hakatere is a medium-sized gravel-bed braided river in the Canterbury region of New Zealand's South Island, flowing approximately 112 kilometres from the Southern Alps to the Pacific Ocean. The river has two main branches: the North Branch draining the Winterslow, Old Man, and Mt Hutt ranges, and the larger South Branch originating from the Ashburton Glacier below Mount Arrowsmith (2,781 metres). The two branches run roughly parallel across the Canterbury Plains before merging just upstream of the town of Ashburton, about 21 kilometres from the coast.

The South Branch offers the most technically demanding paddling, rated Grade III/IV and described as a solid intermediate-to-advanced run. The upper section includes a Grade IV gorge known as the "Gates of Ashvegas," featuring continuous whitewater and a notable chockstone through which paddlers float. The continuous nature of the whitewater demands a competent team at all flows, as a swim could be long and serious. Paddlers wishing to avoid the Grade IV section can put in below the Boundary Creek confluence, though the steep scree and scrub banks may require scouting for a suitable entry point. The run takes approximately 1.5 hours to paddle at moderate flows. A known hazard exists near the takeout: a fence line spanning the channel approximately 200 metres above the takeout, which may be partially submerged at higher flows but presents a real risk at lower water. Paddlers are advised to scout this feature before committing to the final stretch.

The river catchment supports around 14 native fish species, including the threatened Canterbury mudfish, as well as koura (freshwater crayfish) and approximately 48 native bird species. Nationally threatened species present include wrybill, banded dotterel, pied stilt, and black-billed gull — the latter making the river an Important Bird Area as designated by BirdLife International. The river mouth at Hakatere is noted for its dramatic character and is a significant ecological and cultural area for Ngāi Tahu, for whom the waterways hold cultural, spiritual, and historical importance.

Downstream near the coast, the Ashburton–Hakatere River Trail follows the north bank of the river for 19 kilometres from Ashburton to the river mouth, with multiple road-end access points along the way, which may be useful for paddlers planning flatwater or lower-gradient sections closer to the sea.