We're standing on top of a volcano, being shown how fire-fountaining works with the help of Bruce Hayward (author of Volcanoes of Auckland) and a bottle of Coca-Cola.
He's mimicking the volcano's evolution with fizzy spray covering the grass. Science is suddenly a whole lot more interesting to my son when mess is involved, and we're told about the huge crater stretching from the Auckland City Hospital to the Auckland Museum.
Armed with Volcanoes of Auckland, and with the help of Hayward, we're looking at parts of Auckland we've frequently walked past, unaware of the fascinating volcanic history underfoot.
The book helps us find items of interest, like the large volcanic "bomb" nestled between the trees facing the Domain's grandstand. It's like first prize in a treasure hunt when we eventually find it.
Next, it's inside the Wintergarden Fernery to see light frothy scoria rock and then to the duck ponds, which owe their existence to the Domain volcano because all the rainwater falling in the crater passes through cracks in its solidified lava lake to bubble up in the ponds. The overflow can be seen trickling out of a waterfall just across the road.
A few days before, we met Hayward in the basement carpark of the Milford Mall to see clearly visible lava flows underneath the busy shopping centre. Although it's not the most impressive sight, it points out just how much we take our volcanic history for granted, rushing by with shopping bags every week.
Just up the road from the mall, at the boat ramp in Takapuna, signs show sketches of how an ancient forest here would have looked 250,000 years ago. We venture at low tide across the rocks to spot tree moulds formed by the once-flowing lava.
A couple of giant kauri tree "graves" are easy to spot on the walk around the rocks from Milford to Takapuna with the help of pictures in the book. Once found, it's hard to imagine we have never noticed these before.
It's also humbling to stand where proud trees had grown for hundreds of years, only to be felled in minutes by a lava flow. People walk and run past us, unaware of the legacy they are passing.
At Thornes Bay, we're shown tiny waterfalls bubbling up clear, drinkable water from the rock pools near the salty ocean, overflow from the Lake Pupuke crater lake. It feels like a revelation - being in on a private joke or well-kept secret - finding this out. I can't help wondering what other important things in life I am hurrying past.
The book covers the whole Auckland region with around 50 cones and craters.
There's the crater at One Tree Hill that kids can run down and spell out their name with the stones at the bottom, or field trips to Mangere Mountain, one of the least modified of the large cone pa sites once dominant throughout Auckland, as well as discovering lava cowpats on Mt Wellington.
A visit to the Auckland Museum's volcano house with its grim broadcast of a modern volcanic eruption and its aftermath is another place to start the journey. Although it left me wondering why there isn't a snappy volcano or earthquake message like the "stop, drop and roll" in fire safety messages?
Instead, Mark Sainsbury tells us all to take a brochure, which isn't available.
Before our volcanic adventure, I had nervously asked Hayward if he thought there would be a volcanic explosion in our lifetime. I was surprised by his answer: "It would be nice, wouldn't it?"
I now know at least one little boy who agrees.
You can join the Auckland Geology Club: Meetings are held on the third Tuesday of each month, except January, at 7.30pm in the Epsom Community Centre, 200 Gillies Ave, Epsom.