Elevation: 7,369 ft.
Pump Geyser is a cone geyser located in the Upper Geyser Basin of Yellowstone National Park. It is in the Geyser Hill Complex which includes Aurum Geyser, Beehive Geyser, Big Cub Geyser. Doublet Pool, Giantess Geyser and Lion Geyser, among others.
Pump Geyser erupts almost constantly making splashes 2 to 3 feet high, and thumps without an apparent interval, though there are less productive periods. Then, in 1990, Pump became a true geyser, with intervals and durations of a few seconds. A small boil builds up to a heavy doming of the water which triggers bursting eruptions that spray water up to 15 feet high. After a few seconds of this, the activity dies down to a mere simmer, but, after a pause of a few seconds, the cycle starts anew.
It was most likely named by Frank Jay Haynes, the park photographer from 1883 to 1916. It gets its name because its constant eruptions make a sound similar to that of old style mechanical pump.