The town of Rotorua (“Roto-Vegas” to the locals) is situated near the middle of the North Island, in an area where the Earth’s crust is very thin. It’s famous for geysers, boiling mud, strikingly coloured mineral deposits, mineral health spas, hydrogen sulphide fumes, and the chance that the footpath in front of you might suddenly cave in and become a steaming pit (this really does happen sometimes!).

One of my favourite attractions in the Rotorua area is Waimangu Valley. This is a valley filled with native bush, lying under the shadow of Mount Tarawera. Tarawera erupted violently one night in 1886, raining ash, fire, and sulphur for miles around, burying an entire village, killing over 100 people, and shattering the famous Pink and White Terraces (“8th wonder of the world”) into a million pieces. The great gash in the mountain from which the four columns of fire emanated is visible in the top left corner of this picture.

The Pink and White Terraces are no longer there, but the area is still full of steam, geysers, terraces, and history. You take an hour’s walk from the car park through the bush, passing the sites and emerging on the shores of Lake Rotomahana. You catch the boat to see where the terraces lay and to observe the brooding lake and mountain. Finally you return, and take a coach ride back up the hill (optional).

With the children in tow we only did a portion this time. Here is Echo Crater / Frying Pan Lake, a lake of boiling acid water overlooked by the sulphurous Cathedral Rocks. Around the lake are signs to take care and not stray from the path, and the occasional white cross to mark the deaths of tourists who disregarded the warning and were caught by an unexpected geyser. Everywhere are silica deposits forming miniature copies of the Pink and White Terraces – shallow circular basins, nested and staggered like lace or petals. Most were white when we visited – the colours change as the minerals accessible to the hot water are dissolved away – but there was an overlay of yellow sulphur and the green of the warm acid-loving algae.

Beyond the lake was a staircase beside a natural overflow channel. Climbing the staircase leads to Inferno Crater Lake, a brilliantly blue-hued lake fed by a hidden geyser. The lake level oscillates in a complex pattern over a six-week period, and in the middle of the cycle it overflows down the channel into the stream below. The striking blue colour is only visible at certain points in this oscillation, so we were lucky to see it so beautiful – I’ve seen it once when it was a simple flat grey. The lake is 30 metres deep, the overflow water discharges at around 80degC, and the water pH is sometimes as low as 2.1 – so it was not unreasonable of Aidan to be a little scared of it!

We next followed a stream, kept at around 50degC by water from the Frying Pan Lake and other sources. It was filled with blue-green algae and other plants enjoying the warmth and mineral content, and dotted regularly with miniature geysers playing to a height of 20cm or so. Further down (beyond the point we reached with the children) this passes some silica stalactites, the Marble Terrace, the Warbrick Terrace, Rainbow Crater, and runs on down to Lake Rotomahana. We will return here some other time to complete the journey.

That night we stayed in a beautiful lodge just out of Rotorua, on a lake (nearly) of our own. The following morning we headed for the Polynesian Spa, the biggest and best natural mineral baths in Rotorua. We and the kids both loved it, and the water is wonderful for the skin. The keener visitor can also try the thermal mud treatments; we skipped them on this occasion. We chased this with a fabulous lunch at the fabulously quirky and always reliable Fat Dog Cafe.