Mount Ruapehu Crater (NZ)

The hike to Crater Lake at the top of Mount Ruapehu involves a steep track from Iwikau Village up to Knoll Ridge via Waterfall Descent, and then off-track scrambling over rocky terrain and loose scree to The Dome.  

Taking advantage of good weather (rain is forecast later in the week) before we undertake the four-day Ruapehu Round the Mountain hike, we’re up early to tackle the Mount Ruapehu summit. “We” being myself and Jeffrey (we’re part of the same Scout group); a third member of our group (Connor) is doing the Tongariro Northern Circuit and will meet up with us later in the day. Mount Ruapehu is the highest volcano on the north island of New Zealand, with an active volcanic status: the most recent major eruptions were between 1995 and 1996, with additional activity in 2007, and over 60 eruptions since 1945.

The walk starts at Iwikau Village at the end of Bruce Road, not far from our hotel at Whakapapa village. (There are many different unmarked routes to the Ruapehu summit – the easiest approach is from Iwikau village.) As we drive up Bruce Road from Whakapapa, the nearby Mount Ngauruhoe is silhouetted by the early morning sun.

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Arriving at 7:30am, we park close to the base of the Sky Waka gondola, which was opened in 2019. It doesn’t begin operating until 9am, so we’ve decided to walk up and catch the gondola back down to save some time. The track up (called the Watefall Descent) is not marked at the bottom, but is a pretty obvious service trail which goes past snow-making cannons and some chairlift stations that are only operational in winter.

To the north-east the silhouette of Mount Ngauruhoe is visible again.

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About half-way up to the top station of the Sky Waka cablecar, the service road is replaced by a wide and slightly uneven concrete strip. Most likely laid to protect cables or other skifield infrastructure, the slightly incongruous “concrete trail” provides easy walking compared to the adjacent rocky terrain.

As we near the top of the Sky Waka cable car, we pass below the sleek Knoll Ridge Chalet, the upper terminus of the cable car and winner of the “World’s best designed cafe” award by DesignCurial in 2015. It looms over the valley in contrast to a small timber hut that stands alone in the middle of the rocky valley.

As we continue up past Knoll Ridge Chalet, there’s views of the Whanganui national park mountains to the north-west, and across to the chairlift on the Far West Ridge.

So far we have been following a poled route – I suddenly realise we’re going the wrong way… the only route that is marked by poles is the Skyline trail, which goes to the Skyline Ridge. There are no poles or marked routes to the Crater Lake. We need to be heading more directly up the slope, so we adjust course, leave the poles behind and and bear directly north, just above the Knoll Ridge T-bar. The ground is very rocky but not too difficult to walk on.

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We soon reach the base of the Whakapapanui Glacier, which has retreated significantly in the last 50 years, and is now a narrow sliver of snow to the east of Restful Ridge. Even with crampons (or rather, a pair of  Kahtoola MICROspikes which I’ve found invaluable on previous trips) the hard-packed and icy snow is too slippery to walk on. So we follow the glacier up the eastern side, along the rocks (fortunately it’s mostly still rocky terrain, rather than scree). Just visible at the very top of the slope at Glacier Knob is a small hut, the purpose-built ‘Matarangi’ facility that houses volcano monitoring equipment.

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As we climb past the Matarangi bunker to the east, the slope gets much steeper… and changes from rock to loose scree. For every two steps forward we slide back a step. Jeffrey, who’s a convivial hiking companion and rarely short of a joke or story as we walk, falls oddly silent as we haul ourselves slowly up the scree.

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The last few hundred metres seems take almost an hour before we triumphantly reach the Te Heuheu Ridge, just to east of The Notch. From here we are looking directly into the Central Crater and Summit Plateau.

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To the east is the Summit Plateau, with the very distinctive Matihao or Cathedral Rocks (2,663m asl) on the opposite side. The summit plateau consists of several craters: the crater lake (which we can’t see yet) is the active vent and directly below us is the Central Crater.

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To the south is The Dome, our destination, and behind it the dome-shaped Paretetaitonga (2751m), one of three major Ruapehu peaks (the other two being Tahurangi at 2,797m and Te Heuheu at 2,755m). In front of Paretetaitonga is the Whakapapaiti Glacier.

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Looking north you can see the Pinnacles in the foreground, and in the distance Lower Tama Lake in front of Mt Ngauruhoe.

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While the hardest part of the hike now is completed, we need to continue south along the ridge to reach The Dome. From the base of The Dome, there’s a good view of the Te Heuheu Ridge, with Tukino Peak (2,720m) and Te Heuheu peak (2,732m) at the far end.

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The track descends a little at the end of the Te Heuheu Ridge, and then ascends fairly gently up another ridge to The Dome.

From The Dome (2,672m) there’s an incredible panoramic view of Crater Lake and the surrounding mountains.

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The 150m deep, active crater lake lies on top of Ruapehu’s vent and changes in colour depending on the temperature, which varies from 12-45C.  It changes from deep green to pale blue and dark grey as it gets hotter. Today it’s around 30 degrees Celsius, with a period of increased seismicity having been detected a few weeks prior. Behind the lake is Tahurangi (2,797m) in the middle, and Pyramid Peak (2,645m) at the very left of the photo below.

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It’s possible to walk down to the lake, although we didn’t have time. But while it seems an agreeable temperature for a swim, the water is highly acidic with a ph of 1. In the late 1950s and early 1960s it was used for swimming, but higher levels of volcanic activity since 1965 has made the lake more acidic.

Swimming in Crater Lake
Source: Archives New Zealand – Te Rua Mahara o te Kāwanatanga

Looking in the opposite direction (to the north), the late morning sun casts a shadow of the jagged Te Heuheu Ridge peaks on the snow below.

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From The Dome we take a much easier path to the west of Glacier Knob (you can see the Matarangi bunker below perched on top of Glacier Knob below) and down Restful Ridge, avoiding the painful scree we encountered on our ascent.

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We had planned to take the Sky Waka cablecar down from Knoll Ridge, but as we get there we discover there’s been a power failure. So rather than risking a long wait, we set off down Waterfall Descent again by foot. About ten minutes later, as we pass under the Sky Waka cables on the walking trail, we see the cable cars start up again…

 0.0km Iwikau Village at end of Bruce Road (1,573m asl)
 2.5km Bottom of Knoll Ridge Cafe / Sky Waka terminus (2,010m)
 5.0km Te Heuheu Ridge above summit plateau (2,610m)
 5.9km The Dome (2,672m)
 9.6km Knoll Ridge Cafe / Sky Waka terminus
12.2km Iwikau Village carpark
Location Start at Iwikau village at top of Bruce Road. Walk from here up Waterfall Descent or take Sky Waka cable car.
Distance 12km. 6-8 hours from village. 4-6 hours if taking cablecar.
Grade Moderate/Hard. Total ascent is 1,050m.
Season/s November – April (alpine experience needed in winter)
Map/s
GPS Route PlotaRoute map with option to download GPX / KML file
Resources

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