Pohuehue Falls is roughly a 40 minutes' drive away from Auckland. There is a Toll Road if you drive from Auckland. Don't forget to pay NZD 2.30 each way.

From Auckland travel north on the SH-1 for 50 km. The carpark is to the left immediately past the Pohuehue viaduct. There is a long-drop toilet there (at the beginning of the walk) and a couple of picnic tables.

An easy walking 30-minutes' return Waterfall track leads to the waterfalls lookout.  The track starts to descend from the parking, cross the stream via a footbridge and leads to a viewing platform. Unfortunately, the track is not suitable for wheelchairs/strollers.

From the lookout, you've got a limited view of the waterfall. To take a good photo or get a better view you can, with care, descend to the waterfall's base via an unofficial track. Don't attempt to do it if it's rainy or wet. 

Return via the same trail. There is a beautiful cascade en route, just search for an unofficial side track (near a short foot-bridge), which brings you to the top of the cascade.