It is fed by Wainui River and flows generally north, draining into Mangonui Harbour at the southern end of Doubtless Bay.

[1] The river drains the northern edge of Omahuta Forest, runs in a gorge through the Otangaroa massif, then meanders into the Oruaiti estuary, where it is joined by the Kenana River.

The catchment is mainly farmland, pine forest and native bush.

[2] Pollution in the river is classed as fair to good.

[4] The native forest was logged after 2,600 acres (1,100 ha) was sold to Auckland Timber Co for £1,250 in 1878.