Old Faithful Geyser - Yellowstone Park.

Watching Old Faithful Geyser erupt is a Yellowstone National Park tradition. People from all over the world have journeyed here to watch this famous geyser. The park’s wildlife and scenery might be as well-known today, but it was the unique thermal features like Old Faithful Geyser that inspired the establishment of Yellowstone as the world’s first national park in 1872.
Old Faithful is one of nearly 500 geysers in Yellowstone and one of six that park rangers currently predict. It is uncommon to be able to predict geyser eruptions with regularity and Old Faithful has lived up to its name, only lengthening the time between eruptions by about 30 minutes in the last 30 years.
Thermal features change constantly and it is possible Old Faithful may stop erupting someday. Geysers and other thermal features are evidence of ongoing volcanic activity beneath the surface and change is part of this natural system. Yellowstone preserves the natural geologic processes so that visitors may continue to enjoy this natural system.
Watch eruptions from the Old Faithful viewing area or along the boardwalks that weave around the geyser and through the Upper Geyser Basin.
The world’s most famous geyser, Old Faithful in Yellowstone, currently erupts around 20 times a day. These eruptions are predicted with a 90 percent confidence rate, within a 10 minute variation, based on the duration and height of the previous eruption. During visitor center hours, geyser statistics and predictions are maintained by the naturalist staff. This is done by good old-fashioned observation, timing with a stopwatch, and writing in a log book. Visitors can check for posted prediction times in most buildings in the Old Faithful area and on the webcam web page