As a tent was pitched in the clearing at our designated meeting place the pilot simply landed on the gravel of the Waipakihi Rd to pick us up.
After a jaw-dropping ride up the winding river, flanked by towering beech-clad hills, we were deposited on a wide stony bed just below a narrow gorge.
The river and the guides' local knowledge dictated our route back down the river, sometimes over its bed, often through light bush along its banks, or across tussock flats, constantly crossing to find the next path.
We were in the water a lot, but I was never more than waist-deep. As it was a glorious day the river was benign, though the debris on its banks suggested it could rage.
Plenty of breaks, and a long lunch where we lounged beside the river in the sunshine, made it a deceptively leisurely walk.
We learnt about the local environment, the kiwi breeding programme, the mix of Kaimanawa Forest Park and privately owned land we were passing through. A fairly fresh deer carcass was a reminder that hunters love it here.
Legs were just beginning to complain they had done enough, when a steep track from the river bed led us back to our cars.
Though we were returning to this side of Ruapehu the next day for the Lahar Path walk, we chose to stay in our ski club's lodge in National Park Village, an hour's drive away, but much closer to most of the summer programme activities.
Next morning saw us in a totally different environment, on the opposite side of Desert Rd, heading up the four-wheel-drive track towards Tukino Ski Field. We gained altitude rapidly, Mt Ngauruhoe seeming to drop beside us.
Our guide for the day was Harry Keys, conservancy advisory scientist with DOC, who has monitored and managed volcanic activity on Mt Ruapehu since 1990, a fairly uneventful job until Ruapehu obliged with dramatic eruptions in 1995.
Harry took us along the Whangaehu River, down which cascaded the huge lahar (volcanic flood) caused when Ruapehu's Crater Lake broke its banks in 2007. Fortunately, Harry and his team had anticipated this so there was no chance of a repeat of the Tangiwai disaster. He unlocked a box under a solar panel to show us one of the series of warning systems that are continually monitored.
Through his expert eyes, we appreciated the full impact of the lahar, its power illustrated by the large boulders sitting in ungainly places and a deep gorge made 12m shallower by the muck left behind.
Harry had us raft up in groups of four when we needed to cross the narrow, stony river.
Otherwise, we progressed along its banks by clambering rocky faces, climbing scree, walking over lava flows thousands of years old, rubbed smooth by lahar.
We stopped for lunch after crossing a swing bridge spanning a deep chasm. Just along the track, a sign stated clearly: "Extreme lahar risk next 400m. Do not stop in this area. Do not proceed past here if you hear a loud roaring noise up river."
Further down river, below a couple of thundering waterfalls, a circular cave further demonstrated the force of lahar flow.
If the walk across the desert to the cars did get a bit tedious, it was worth it for a day that was a combination of fascination, education and exhilaration.
Checklist: Tongariro/Taupo
* Further information
The DoC Summer Programme runs from December 30, 2009 to January 30, 2010. For details and bookings visit www.doc.govt.nz
