As one of the most accessible of the Great Walks of New Zealand, the Tongariro Alpine Crossing is also one of the most popular.
Since the 1990s the numbers on the track have increased tenfold, to around 130,000 annually, with the snake of tourists trekking the alpine trail earning the nickname a "conga line".
Sam Clarkson, owner of iconic Skotel Alpine Resort, has been a guide on the crossing since the 1990s.
"In the 90s we had the eruptions of 1995-96 and then in 1998 there was this terrible snow year," he said. "Everybody thought 'we are going to have to do better than to rely only on the ski area'. A lot of people started to think the Tongariro Crossing is probably quite good to promote in summer.