Why it matters

Every thermal park in this district sells you steam and heat. Wai-O-Tapu sells you colour, and the colour is not decoration — it is the visible chemistry of one of the most extensive geothermal systems in New Zealand, which the operator puts at some eighteen square kilometres underground. What surfaces here surfaces carrying dissolved metals, and each one drops out of solution as a different pigment.

The Champagne Pool is the centrepiece and it is worth knowing what you are looking at. The crater is about sixty-five metres across and roughly sixty-two metres deep — deeper than it is wide — and the water sits at between 73°C and 75°C. The bubbles that give it its name are carbon dioxide, coming off continuously, which is why the surface fizzes rather than boils. And that famous orange rim is arsenic and antimony. The fluid is oversaturated with orpiment and stibnite — arsenic sulphide and antimony sulphide — which precipitate out along the shallow edge and build the ledge you photograph. It is one of the most beautiful things in New Zealand and it is made of two classic poisons.

On the pool's age, the published figures do not agree and we could not settle it. The commonly repeated figure is that it formed about nine hundred years ago in a hydrothermal eruption; more recent volcanological work on the eruption that made it points to something closer to seven hundred. We were unable to open the underlying papers to check either directly, so we are not going to pick. Take it as somewhere between seven and nine centuries — which is the interesting part anyway. On any reading this pool is younger than the cathedral in your nearest city.

The rest of the park is the same trick in other colours. The Artist's Palette is a shallow sinter flat where the shading shifts with the wind and the water level; the Devil's Bath is a flooded crater of a green so saturated and so wrong that most people's first reaction is to assume it has been dyed. It has not. It is sulphur and ferrous salts in suspension, and it changes.

What it's like

The first surprise is the scale of the walking. This is a large site laid out as loops of well-made boardwalk and gravel path, and you move through distinct rooms of landscape rather than around a single feature — craters, then terraces, then a flat pale plain, then bush, then the pool. The second surprise is the smell, which is stronger here than in the city and comes and goes with the wind rather than sitting steadily.

And the third is that the colours are genuinely as advertised, which is not usually true. Photographs of the Champagne Pool look enhanced and are not; the orange really is that orange, and it sits against a pool of pale steaming grey-green under a rising sheet of vapour that periodically hides the whole thing and then clears. Most of your time here is spent waiting for wind. Cameras out, everyone standing still, watching a curtain of steam decide whether to lift.

How to visit

Getting there. From Rotorua, head south on State Highway 5, the Thermal Explorer Highway, for about twenty-seven kilometres until you reach the Waiotapu Tavern, then turn left opposite the tavern and go two kilometres. The operator's own table gives it as 31km and twenty-seven minutes from Rotorua, and 52km and thirty-seven minutes from Taupō. There is a shuttle operator and Intercity serves the area, but this is a place built around arriving by car, and the two-site layout makes that more true rather than less.

Hours. Open 8.30am to 4.30pm, seven days, with last admission at 3pm, closed Christmas Day. Allow one to two hours for the park on top of the geyser.

Use the lavatory before you go through the gate. This is not a small point. The operator states plainly that there are no toilet facilities in the main park or at the geyser site — only at the Visitor Centre. On a two-hour circuit, with children, in a place whose whole business is hot water, that is worth planning around.

On access, the restrooms at the Visitor Centre include a disability provision and a baby-change, mobility parking is at the front of the centre, and the park's main walk is passable with a stroller. At the geyser, most of the parking is within about a hundred metres of the seating.

Making the most of it

Know before you drive out that the geyser is helped along, because the operator will not tell you in those words. Wai-O-Tapu calls it, on every page, a "presentation". What happens is that a surfactant is dropped into the vent to trigger the eruption at a set time, which is why a natural feature can be advertised to the minute. This is not a swindle and it is not new — the effect was discovered by prisoners working here early last century, who found the spring erupted when they used it to wash their clothes, and it has been done daily ever since. It is a hundred-year-old piece of theatre with a real geyser at the centre of it. But you should know, rather than find out afterwards, and the word presentation is doing a lot of quiet work.

If you are two adults with three children, buy the family ticket and not the singles. Two adults and three children bought separately is NZ$145; the family ticket is NZ$115 and covers exactly that.

Stop at the mud pool on your way past, and do not pay for it. The Waiotapu mud pool — the largest in the country, sitting in the crater of a mud volcano that eroded away in the 1920s — is on Waiotapu Loop Road with its own parking, and it costs nothing. GeoTrips describes it as a two-minute walk on a track "suitable for wheelchairs". It is the best free geothermal thing in the district and a great many people drive past it twice.

Go on a still day if you have the choice. The steam is the enemy of the view and of the photograph. Wind clears it, and also drives it straight into your face; a calm bright morning after rain gives the strongest colour.

Bring a card. The site takes no cash at all, at either gate or in the café.

Nearby

This stretch of State Highway 5 south of Rotorua is the densest run of geothermal sites in the country, and Wai-O-Tapu is at the far end of it. Maunga Kākaramea — still signposted and still widely called Rainbow Mountain — is a few minutes back towards Rotorua, with a crater lake walk of about thirty minutes return, graded easiest, and free. Waimangu Volcanic Valley is on the same road again, closer to the city, and is the other big paid site out this way; between them they make a full and slightly overwhelming day, and most people are better off doing one of them properly.

The Waiotapu Tavern, at the turnoff, is the landmark you navigate by and a reasonable lunch stop in an area with very few of them.

Further south, Craters of the Moon at Taupō is the cheap comparison and the useful one — a geothermal field with a boardwalk and a ten-dollar ticket, and no colours at all. Going to both in a day tells you more about what makes Wai-O-Tapu unusual than either does alone.