The Tongariro crossing, over a volcanic plateau in a day

The volcanic plateau in the centre of New Zealand's North Island is one of the most remarkable landscapes in the country. Three great volcanoes rise from it. Ruapehu, the highest mountain on the North Island, is a broad, snow-capped massif with a crater lake at its summit and ski fields on its slopes. Ngauruhoe is a near-perfect cone of loose scree, much younger than its neighbours. Tongariro, the oldest, is a complex of craters and vents. All three are active. Ruapehu has erupted several times in living memory, and in 2012 a vent on Tongariro erupted, showering part of the walking track with rocks.

The mountains are sacred to the Ngāti Tūwharetoa people. In 1887 their paramount chief, Te Heuheu Tukino IV, gave the peaks to the nation, to protect them, and they became the heart of New Zealand's first national park. Tongariro National Park is a World Heritage Site for both its natural and its cultural significance.

The crossing

The Tongariro Alpine Crossing runs for about nineteen kilometres across the flanks of the volcanoes, from the Mangatepopo valley on one side to Ketetahi on the other. It is a one-way walk, so transport is needed at both ends, and it takes most people six to eight hours.

From the start, the path follows a valley of old lava flows to the foot of the Devil's Staircase, a steep climb up to the South Crater, a flat, barren basin between Ngauruhoe and Tongariro. From there, the climb continues along a ridge to the highest point of the crossing, at the rim of the Red Crater. Its walls are stained deep red and black by the heat and minerals of the vent, and steam still rises from the ground.

Below the Red Crater lie the Emerald Lakes, three small crater lakes coloured startling shades of green and turquoise by minerals dissolved from the surrounding rock. The descent to them is down a slope of loose scree, which most walkers half-run, half-slide. Beyond, the path passes the Blue Lake, which is sacred to Māori, so visitors should not swim in it or eat beside it. It then descends past steaming vents and down through tussock and forest to the end.

How hard it is

The crossing is often described as one of the finest one-day walks in the world, and it is popular, with hundreds of walkers on a fine summer day. It is not to be underestimated. It is long, steep in places and largely exposed, with the high point at nearly nineteen hundred metres. The weather on the plateau can change rapidly, from sunshine to wind, rain, cloud and even snow, in any season. People are regularly caught out, and some need rescue. Good boots, warm and waterproof layers, food, plenty of water and a good weather forecast are essential, and it is wise to turn back if the weather turns.

The best season is the southern summer, from about November to April. In winter the crossing becomes an alpine route, needing ice axe, crampons and experience, or a guide.

Lake Taupō, to the north of the volcanoes, is the largest lake in New Zealand, and it is itself the crater of a volcano. It fills a caldera left by enormous eruptions, the most recent of them about eighteen hundred years ago, one of the most violent anywhere on earth in that time. Today the lake is calm, clear and popular for trout fishing and boating, and the town of Taupō, on its northern shore, looks across the water to the snow-capped peaks of the plateau. Mount Ngauruhoe, the most perfectly shaped of the three volcanoes, stood in for Mount Doom in the films of The Lord of the Rings.

The walking tours

Explore Worldwide's Walking in New Zealand, eighteen nights in November, January and February, includes Tongariro National Park. Its other places include Auckland, Rotorua and Wellington, and in the South Island the Marlborough Sounds, the Queen Charlotte Track and Motuara Island, Havelock, Abel Tasman National Park, Nelson, Westport and Punakaiki.

Explore Worldwide's New Zealand Explorer, eighteen nights from November to March, includes Taupō, on the lake beside the volcanic plateau, along with Auckland, Matamata, the Bay of Plenty, Napier, Wellington, Picton, Nelson, Abel Tasman, Hokitika and Fox Glacier.

Start early, carry more water than you think you need, and don't rush the Emerald Lakes. There are few places on earth where you can walk across a living volcano in a single day, and fewer still with a view like this.