Champagne pool. Steam rises from a geothermal (hot) pool known as Champagne Pool in New Zealand, while carbon dioxide bubbles to the surface. Water from this pool contains silicate of lime (sinter) deposited as the water evaporates. The sinter has formed the largest geothermal terrace in New Zealand. At a temperature of 74 degrees Celsius, and pH of 5.4, the acidic chloride water contains gold, silver, mercury, sulphur, arsenic, thallium, antimony, and other minerals. The pool is 60 metres in diameter and 60 metres deep. It was formed 900 years ago in the explosion crater of a volcano. Photographed at Waiotapu (Maori for insSacred Waterins) on North Island.