About 10 kms to the southeast of Reefton, you will find the entrance to the Inangahua Swingbridge. This is also the start point for the Progress Water Race Track which you can follow to the Big River Track. These tracks were initially developed to access gold bearing reefs in the surrounding hills and mountains.
If you are short of time, cross the swingbridge and walk up the track for a while into the Victoria Forest Park. The river itself is pretty and the track starts by climbing up through stunning beech forest.