The Mangamuka River flows south-east from the Maungataniwha Range, running alongside State Highway 1 before emptying into the northern arm of the Hokianga Harbour. The river is approximately 30 kilometres in length and, for the most part, carries a near-nil gradient, resulting in sluggish current through much of its lower reaches.

Above Mangamuka Bridge Settlement, the river passes through a short rocky gorge beside the main highway, where it is quite scenic but very small — too small for practical river-based recreation in that section. Below the gorge, as the river leaves the bush-clad hills and enters the rural lowlands, it becomes very flat with low gradient and is useable by canoes and kayaks. Motor launches and jet boats can access the river up to 14 kilometres from the mouth, as far as Mangamuka Bridge.

The lower reaches are characterised by willows lining the banks, transitioning to mangroves closer to the harbour. At low tide, the muddy banks in this tidal section are unpleasant, which is a practical consideration when planning a trip. The overall scenic value of the river is rated as moderate above the bridge settlement, but the rural landscape of willows and mangroves in the lower section is generally considered uninspiring. The recreational value is rated low overall.

Paddlers considering this river should be aware that willows are noted as a problem along much of its length. The tidal influence on the lower section means timing a paddle around the tide will significantly affect the experience, particularly to avoid exposure to muddy banks at low water. There are no notable hazards beyond the shallow, small nature of the upper reaches and the tidal, low-gradient character of the lower river. The river is not considered suitable for pack floating in the upper reaches due to its small size, and the lower section's shallow flow and minimal gradient make it unsuitable for that purpose as well.