Mangamuka is a district in Northland, New Zealand, at the junction of the Mangamuka and Opurehu Rivers. State Highway 1 runs through the area, and the settlement of Mangamuka Bridge lies at the point where the highway crosses the Mangamuku River. The river runs into the upper Hokianga Harbour. Just to the north west, the highway runs through Mangamuka Gorge in the Maungataniwha Range. Umawera lies to the south east.