Old Faithful

geysers · Yellowstone · nature's power · predictable

Erupts like clockwork. Old Faithful shoots steaming hot water and steam high into the air about every 92 minutes on average. Sometimes it waits as little as 35 minutes between eruptions, and sometimes as long as 120 minutes, but it's so regular that visitors can plan their day around it.

Powered by heat underground. Deep beneath Old Faithful, hot rocks from Earth's interior heat water that gets trapped underground. When the pressure builds up enough, the water suddenly explodes upward through cracks in the rock, creating the dramatic eruption.

Located in Wyoming. Old Faithful sits in Yellowstone National Park, one of the most famous national parks in the United States. It's so beloved that an inn was built right next to it so visitors could watch the eruptions.

Named in 1870. Explorers on an expedition gave Old Faithful its name because they were so impressed by how reliable and faithful it was to its eruption schedule. It was the very first geyser in Yellowstone to get its own name.

Cone geyser shape. Over hundreds of years, the minerals in the erupting water have built up into a cone shape around Old Faithful's opening. This special cone structure helps contain the pressure that builds before each eruption.