Since then, the southern portion of the river has flowed into Lake Wahapo, while the northern section discharges into the Tasman Sea north of Ōkārito Lagoon.

[3] The Waitangitāhuna river rises in the snowfields of the Tatare Range, on the slopes of McFetrick Peak, and flows in a generally northern direction.

[3] Following the 1967 avulsion, some of the flow from the alluvial fan was into Graham Creek and then back into the original bed of the river and to the Tasman Sea.

[3] The southern section of the river flows for about 21 kilometres (13 mi) from its headwaters to Lake Wahapo,[3] and includes a 57-metre-high (187 ft) waterfall.

[9] The northern section of the river, flows generally north then westwards for approximately 28 kilometres (17 mi) from its source at the confluence of Graham Creek and Matainui Creek (which flows through Whataroa) to its mouth at the Tasman Sea,[3] just north of Ōkārito Lagoon.