Onwards to the thermal pools and geysers.

You are certainly aware that you are in volcano country in New Zealand from the shape of the young hills/mountains, the black sands and the steam rising from forests and rocks.
We headed on to Rotorua where we visited the famous 'baths' at the Museum and went underground to see how they built them, then on to the thermal pools at Wai-O-Tapu where the colours of the pools, which if you can bear the smell, are phenomenal. The mineral elements give the pools their different colours e.g yellow/primrose is sulphur; white is silica; red brown is iron oxide; purple manganese oxide; orange antimony; green a wonderous lime green is colloidalsulphur/ferrous salts (I had to look that up I didn't remember all the names!!!) and black is the carbon and sulphur. Amazing to see in the thermal pools area, where there are pathways and board walks to wander along. Watching the geysers was also interesting as the guide explained how such events happen and when and how in one instance they can make it happen by pouring a soap like substance down the cone to break the water tension and after a couple of minutes the whole thing erupts - pretty amazing for a non scientist like me.