The Waitaha River is located on the West Coast of New Zealand's South Island, accessed via Waitaha Road off State Highway 6, south of Ross. The river is widely regarded among kayakers as offering one of the greatest concentrations of high-class whitewater runs in a pristine wilderness setting in New Zealand. It is classified as a Class V river overall, though it contains Class VI sections. The overall Class V rating reflects the ability to portage the most extreme sections rather than paddle them all. The upper Waitaha River and Morgan Gorge are considered the pinnacle of hard whitewater kayaking in the country, and the river holds national status in New Zealand whitewater guidebooks, including Charles (2006, 2013) "New Zealand Whitewater: 125 Great Kayaking Runs."

Access to the upper river and its key runs requires helicopter access — this is one of 14 Class V rivers on the West Coast that can only be reached by air. The runs are tight, steep, and difficult to scout in certain sections. The Morgan Gorge, a defining feature of the river, was not successfully paddled in full until 2010, and the upstream Windhover Gorge — which features higher waterfalls and a steeper gradient — was first descended in 2013. The gorge environment is described as naturally unsafe, very difficult to access, and extremely difficult to exit. Rescue skills are considered as critical as paddling skills on these sections. One documented incident involved a team unable to retreat upstream or portage, requiring a seven-hour climb out and a nine-hour round trip the following day to retrieve boats.

The lower Waitaha River, below Morgan Gorge, offers a comparatively easier paddle and is accessible by road. Some kayakers use this reach as a standalone run or as an exit from Morgan Gorge, though overall recreational use of the lower valley is limited despite its accessibility.

The river flows through spectacular gorge scenery with notable natural features including hot pools near Morgan Gorge. The surrounding valley contains conservation land managed by DOC, with huts including Kiwi Flat Hut accessible via the Waitaha Valley. Given the extreme nature of the upper runs, only expert paddlers with strong rescue skills should attempt the upper river and gorge sections, and going with someone knowledgeable about the access and the run is strongly recommended.