From the Historic Howe Truss Bridge take the gentle benched track that runs beside the true right of the Manganuku Stream.
After about an hour you will get to a directional sign, from here head down to the river to a good swimming hole in the Manganuku Stream.
From here you can continue walking upstream in the river for 2 hours approx and you will arrive at the Manganuku Hut. The river exit to the hut is marked with a large orange track marker. There are some deep stream crossings if river levels are high so check before you leave.