In New Zealand’s Rotorua town, vents in the ground puffing out clouds of steam are a common sight

Pohutu is famous for being the most reliable geyser when it comes to eruptions, with eruptions that last for several minutes to hours.

As the smoke from Pohutu, the southern hemisphere’s largest active geyser, settled down after a few minutes of spectacular eruptions behind me, I was left awestruck. This was an unexpected encounter with a rare natural phenomena — geysers — in New Zealand’s Rotorua town in the heart of the North Island. One of the oddest things I saw while driving into Rotorua earlier that morning were random vents in the ground, between houses or by the roadside, puffing out white clouds of steam.

A few months ago, a woman in the city woke up to find a spewing mud volcano in her backyard, forcing the family to evacuate immediately. While that may be uncommon, steam vents (or fumaroles) are quite usual in Rotorua, a city that sits inside the caldera of a collapsed supervolcano that last erupted 25,000 years ago. But the region is still super-active geothermally.

Te Puia, a centre for Maori cultural experiences in Whakarewarewa Geothermal valley, lies just three km from the town centre. It was established and developed predominantly to preserve and propagate the culture of the Maoris, the indigenous Polynesian people of New Zealand. It is spread over 70 hectares in a geothermally active region that includes several geysers, hot springs and mud pools. Considering Maoris have lived here for about 700 years and geothermal pools have been an integral part of their culture, it is, perhaps, fitting that Maori knowledge centre is surrounded by the natural wonders that shaped their lifestyle.

Not equipped with this knowledge prior to my visit, I walked into the centre, fully expecting to see Maori cultural performances and art displays. But I was intrigued when a guide announced we would be taking a break from the tour because the geyser was erupting. Pohutu, the star of the eight geysers in this valley, erupting up to 20 times a day, was sending water up to 30 m into the air.

Billowing smoke rose above the green foliage in the distance as we walked towards the viewing platform overlooking the sinter terraces, fringed by dense forest and layered mountains. Giant ferns lined the spring that was fed by the hot pools. Smoke rose out of vents by the streamside below, filling the valley with ethereal mist that glowed like gold in the sublime evening light. By the time we reached the viewing platform, the geyser was ready to erupt. It began with faint whistling sounds, a spray of hot water that turned into lukewarm mist when it landed on us and an inescapable stench of sulphur.

At full strength, the geyser was spewing water as high as 10 m and a whooshing sound and blinding smoke accompanied the spectacle.

Pohutu is famous for being the most reliable geyser when it comes to eruptions, with eruptions that last for several minutes to hours. Once, in the 2000s, it is reported to have erupted for over 250 days. Geysers are often confused with hot springs, but unlike the latter, where the groundwater is simply geothermally heated, the former requires a unique set of specific conditions to exist. It requires magma to be close enough to the surface to heat the rocks, a water reservoir close to the magma where heated water builds up the pressure in the reservoir, and an escape vent for the built-up pressure to escape. The hot water erupts from time to time through the vent, depending on the pressure build-up in the reservoir below.

The thing with geysers is that they are quite rare, famously irregular in eruptions, and only about a thousand geysers are found in the whole world. About 50 per cent of them are found in America’s Yellowstone National Park, some in Russia and some in Iceland in the northern hemisphere. In the southern hemisphere, Chile, Papua New Guinea and New Zealand have a handful of geysers. I had ended up at the site of the largest geyser in the southern hemisphere quite inadvertently. I was so awed that I kept mixing up words. “Geysers, not glaciers,” said my fellow traveller for the umpteenth time that evening in Rotorua. “Yes, geysers, not glaciers,” I repeated, with an embarrassed laugh. As the swooshing sound of the geyser faded, I walked away thinking to myself that if there’s one thing New Zealand has too much of, it is undoubtedly natural wonders.

Neelima Vallangi is a travel writer and photographer

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