Distance: 5.5 km (3.0 DOC hours) - Unmarked route, hard - Moderate-hard terrain
Altitude: 648m to 1570m. Gain: 1286m. Loss: 460m . Gradient: 19 deg (Steep)
Skills: Occasional scrambles (3/7) - Occasional rivers (3/6)

Unmarked route, hard (8/9)
Unmarked route, no clear geographic features to follow

minor (5/5)
A viable route, not widely used

Steep (difficulty: 5/5)
Steep climbs of >1000m

Moderate-hard (difficulty: 4/5)
Tall, walkable scrub / large rocks, occasional waterfalls or gorges in rivers

Occasional scrambles (difficulty: 3/7)
Tramp with some scrambles and exposure to falls

Occasional rivers (difficulty: 3/6)
Occasional rivers - impassible after heavy rain

Unknown (difficulty: 0/7)
Not specified

This route gains access to the Porter Ridge. My original intention was to complete a traverse of the Porter Ridge, having traversed the Red Hills Ridge from Red Hills Hut, via Red Hill / Maungakura and back via Hunters Hut and Porters Creek Hut in February 2020. However, it soon became clear that the Porter Ridge was as rough as the Red Hills Ridge in places, with very similar rock and terrain to the Red Hills Ridge, not surprisingly. I therefore camped above the tarn and returned via the same route. This is a suitable route to access Porter Ridge and Porter Knob. The spur is steep, and requires some pushing through mainly manuka and dracophyllum scrub, especially in the first 1-200 metres of ascent. After this it is quite easy to pick a route between the scrub, with good footing and regular ultramafic rock giving good footing. Nearer the top, above about 1,200 m, the tussock is difficult to walk through, with large holes between the clumps, even though the gradient is lower than the spur. Eventually crops of ultramafic rock allow easier travel, although the rock is extremely abrasive, as noted by Madpom in the Red Hills ridge route. It is also jumbled with large gaps between rocks and some moving under foot. On the ridge, south west of point 1566, there are huge jumbles of this rock which are impossible to walk over, although the slope is suitable to walk below it to the west. The ridge at point 1566 is reasonably easy travel. LINZ imagery shows similar and larger clumps further along the ridge (Points 1634, 1635, 1676, and 1667). I considered walking further along the Te Araroa Trail to the base of the spur leading from the saddle below point 911 and head of the Porter Creek, then taking the spur to the ridge. Having viewed this from my route I would not recommend it, as it is very undulating, very steep on either side, and appears to also have large clumps of rock similar to the Porter Ridge. Because of the steepness either side, this may be very difficult to navigate around.

Note: Described in the reverse direction to your journey

I took the same route down, which was relatively straight forward to find.