Geysers erupting in a geothermal area. These geysers are the Prince of Wales Feather geyser (left) and Pohutu geyser (centre), in the geothermal area of Whakarewarewa, near Rotorua, on New Zealands North Island. A geyser is a deep natural well in a geothermal rock fissure. The water is heated by surrounding rocks until it is well over its normal boiling point. The pressure prevents it boiling until a critical temperature when the superheated water boils and erupts upwards. The Pohutu getser can erupt to a height of 30 metres, and usually erupts every hour.
