How does a geyser work?

         Geysers are a stunning sight as they shoot huge jets of hot water high into the air. They are only seen at relatively few of the world's active hot springs, with the main ones being in Yellowstone National Park, USA, Dolina Geizerov, Kamchatka, Russia and EI Taito, Chile. The eruptions can occur at regular intervals or be entirely unscheduled, depending on the way in which water flows into the underground caverns where it is heated by volcanic activity. The pressure gradually builds up as water is heated to temperatures above boiling point. Only when the temperature is well above 100°C, do steam bubbles start to rise through narrow channels leading to the surface, blasting fountains of mineral-charged water and steam high into the air.