A natural spring or fountain which discharges a column of water or steam into the air at more or less regular intervals. It may be regarded as a special type of spring. Perhaps the best-known area of geysers is in Yellowstone Park, Wyoming, where there are more than 100 active geysers and more than 3000 noneruptive hot springs. Other outstanding geysers are found in New Zealand and Iceland. The most famous geyser is probably Old Faithful (see illus.) in Yellowstone Park, which erupts about once an hour. Then for about 5 min the water spouts to a height of 100–150 ft (30–45 m). Other geysers are less regular, but some intermittently discharge water and steam to heights of 250 ft (75 m) or more.