A geyser is a spring from which columns of hot water and steam gush into the air every now and then. Today, we call any such spring a geyser. That name comes from a single hot-water spring in Iceland called the geysir, or “gusher.”
The geysir is in a valley that contains more than 100 hot springs. When calm, the geysir is a circular pool of hot water, about 60 feet across. But every so often, the geysir explodes, sending a stream of water up to 180 feet in the air!
Some geysers, such as Old Faithfull in Wyoming, erupt at regular intervals. But a visitor to the geysir in Iceland can never be sure when the spring may erupt. Sometimes it erupts every six hours or so, while other times, 30 or more hours may pass without an eruption.