From the track junction, the marked route passes the first gorge, and drops to the streambed. Markers continue, crossing to the true right (west) and later climbing the face. However, this route is not advisable, and is not maintained. The riverbed provides rapid and easy travel, and is far preferable to an unmaintained, overgrown, windfall-blocked former track
For the first 300m the riverbed is of large rounded slippery river rocks and riverbank travel is preferable to the riverbed. 300m downriver from the junction, a second gorge is encountered. This can be passed in-river in low-moderate flows and was knee deep when I passed through. One deep pool required a scramble on rocks beside it, but otherwise it was a simple walk. If you did need to bypass the gorge, the valleysides are steep and high, and a prolonged climb would be required.
Below the gorge the riverbed is of fine pebbles and provides excellent travel. A third and final gorge is encountered 1km below the junction. A good route exists over a spur on the true-right (east) but was not marked at the upriver end. Good ground trails however, climb 20m onto a spur and then drop back to the river downstream.
Beyond this travel is in the broad flat riverbed all the way to the hut. Two spots of windfall required climbing over when I visited, but nothing prolonged. Just before you reach the hut, a broad sandy flat opens on the true right (west) with low kanuka scrub and littered with driftwood. The hut lies out of sight on the bushedge at the downriver end of this flat. The track to it is not marked, but once out of the river and onto the flat the hut can be seen. The location shown on topomaps for the hut is correct.
Note: Described in the reverse direction to your journey
The route upriver from Lower Matakuhia Hut is painted as a nightmare in both lower and upper hut books, but I found it a relatively easy riverbed route. I can only guess that either a) previous visitors had tried to follow old overgrown or non-existent sidle tracks, or that the riverbed formerly contained a lot of windfall which has since rotted / been washed away.
After crossing the clearing above the hut, I returned to the riverbed - still a broad, flat flow over good fine river pebbles. Two spots of windfall required scrambling over in the first km or so, but nothing hard or prolonged.
1km below the track junction, 1 slot gorge interrupts the good travel. Going upriver black/white marker tape marked the start of s short route over a low spur, bypassing the gorge on the east (true left) and returning to flats upriver. There were no markers on the route itself, nor at the upriver end, but the ground trail was well used and easy to follow.
300m below the junction a second gorge is encountered. The valleysides on wither side are steep and high, and climbing round would involve a long climb, so I walk through in the river instead. 1 pool required a brief scramble on rocks to bypass, but otherwise it was ok through the gorge in low-moderate flows - knee deep.
Above the gorge the easy-going river pebbles and and large rounded slippery river rocks take over - the river banks become more attractive places of travel. Out of nowhgere DOC triangles start - first on the true right, then crossing to the true left (east). These climb the eastern bank above a third gorge, the track uncut but followable. 10-15m above the river, atop a spur and adjacent to a small confluence, a signpost marks the junction of the Matakuhia and Opureke Tracks, and the mid-point (n time) between the two huts.
The DOC signposts say 2hrs from here to either hut, and given it took me 1hr to each I'll stick with this 2hr DOC time. However, be aware that many people reported trips of up to 7hrs between huts.