The Rakeahua River flows through the southwest of Stewart Island (Rakiura), New Zealand, and is accessible by kayak from Paterson Inlet. Paddlers typically cross Paterson Inlet from the Oban area, making their way to the southwest arm and navigating through a maze of sandbars to reach the river mouth. From there, the river can be paddled upstream to a Department of Conservation hut that provides bunks, rainwater catchment, and a small woodstove — a practical overnight option for those combining paddling with a multi-day trip.

The river carries dark, tannin-infused water, a characteristic common to waterways draining through the island's peaty, forested terrain. Tea trees and spiky flax line the banks, and the channel narrows progressively as you move upstream. The surrounding forest supports abundant birdlife; bellbirds are notably vocal along the river corridor. Kiwi have also been reported in the vicinity of Rakeahua Landing, though sightings are not guaranteed.

Stewart Island's weather is a significant planning consideration. Conditions can shift rapidly, with strong winds capable of building whitecaps across Paterson Inlet and making the open-water crossing challenging or dangerous. The crossing from Oban to the southwest arm involves exposed water, and paddlers should be prepared for wind and swell. The island sits at a high southern latitude, and weather can deteriorate quickly regardless of season.

The river is also used by trampers on the Southern Circuit track, and at least one visitor has been noted pack-rafting the river as part of an adventure route. Kayak rental has been available locally in Oban, though availability may vary. The overall paddling experience on the Rakeahua combines a sheltered, atmospheric river paddle through dense native bush with the logistical demands of an open-water approach across Paterson Inlet, making it best suited to paddlers comfortable with variable coastal conditions and self-sufficient travel.