The Whakapapanui Stream is located within Tongariro National Park on New Zealand's North Island, flowing through beech forest and eventually combining with the Whakapapaiti to form the Whakapapa River. The stream offers two distinct paddling experiences: a waterfall section at Tawhai Falls and a longer river run down to Whakapapa Dam.

The Tawhai Falls section is a park-and-huck waterfall run rated Class IV+ to V-. The Tawhai Falls access on State Highway 48 serves as both put-in and take-out, making it a short-shuttle affair. The falls stand approximately 20 feet tall. Flows are visual only, with a recommended range of 50 to 400 cfs. The run is year-round but dependent on rainfall, as the catchment is small and the stream can drop very low between rain events. At lower flows the drop is relatively straightforward; paddlers should avoid letting the bow lift and stay left of the green water on the right side of the falls. The falls are reportedly the inspiration for Gollum's waterfall in the Lord of the Rings films.

The longer river run extends from a road bridge on SH47 to Whakapapa Dam, covering approximately 10 kilometres with a shuttle of around 10 kilometres. This section is described as easier and more scenic than its western counterpart, the Whakapapaiti. The gradient is described as a technical gorge with stunning scenery. Like the falls section, this run is rain-dependent due to the small catchment. Below 20 cumecs the river becomes very scratchy and difficult to paddle. Above 50 cumecs the run becomes a demanding, continuous ride with few opportunities to exit or reconsider. The recommended flow window is 20 to 50 cumecs, assessed visually.

The surrounding landscape includes storm-damaged beech forest in various stages of regeneration, waterlogged clearings, and views of the Tongariro volcanic peaks. The area receives significant rainfall, which is both the primary challenge and the enabler of good paddling conditions. Paddlers should be prepared for rapidly changing flows given the small catchment size.