The Hakaru River flows south through the township of Hakaru, joining the Topuni River and then the Oruawharo River, both of which are tidal arms of the Kaipara Harbour. The river runs approximately 30 kilometres in total length (including the Topuni River), with an average gradient of 1:471, or roughly 2.1 metres per kilometre, making it an essentially flat waterway.

The river is canoeable from the Hakaru Bridge, where paddlers can put in and travel downstream through meandering hill country. The gradient is minimal and there are few rapids, rating the river at Grade 1. The lower section near the Main Road becomes tidal, and the Topuni River is navigable by small power craft and jet boats to a point just beyond the Main Road. Willows line the river for most of its length, and many have fallen into the stream, creating obstructions that paddlers will need to navigate around. This is the primary hazard on the river.

The surrounding landscape is predominantly farmland with patches of scrub and gorse on the hillsides and in the gullies. In the lower reaches near the Main Road, the character of the river changes as it becomes tidal, with mangroves growing on the muddy banks. There is some local use of the river for swimming around the Hakaru area.

Drift boats and rafts are not used on the river. The overall recreational and scenic value of the Hakaru River has been assessed as uninspiring and insignificant, reflecting its character as a slow, willow-lined agricultural waterway rather than a destination paddling river. Paddlers seeking technical challenge or notable scenery are unlikely to find it here, but the flat Grade 1 water may suit beginners or those looking for a low-key outing in a rural setting.