New Zealand's most colourful geothermal field, where the underground boils right at the surface: Champagne Pool is a 74-degree crater rimmed in orange arsenic and antimony, and the Artist's Palette slides from green to pink to sulphur yellow. The air smells of rotten eggs and you stop noticing within ten minutes. The Lady Knox geyser goes off at 10.15 sharp, with a little encouragement.