Old Faithful is a cone geyser in Yellowstone National Park in Wyoming, United States. It was named in 1870 during the Washburn–Langford–Doane Expedition and was the first geyser in the park to be named. It is a highly predictable geothermal feature, erupting on average every 92 minutes, with the period between eruptions ranging from as short as 35 minutes to as long as 120 minutes. The geyser and the nearby Old Faithful Inn are part of the Old Faithful Historic District. This photograph shows Old Faithful erupting in 2022.

Yellowstone National Park was founded on March 1, 1872, and is considered the world’s first national park. It is located primarily in the state of Wyoming, but also extends into Montana and Idaho. The initiative to establish the park was based on scientific expeditions from 1869 to 1871, which documented the unique landscape. President Ulysses S. Grant signed the protection law.

The park covers approximately 8,983 km² and is located on a massive volcanic hotspot. About half of all geysers worldwide are found here. The Old Faithful geyser, which erupts approximately every 90 minutes, is famous. In addition to geysers, hot springs, mud pots, and the colorful Grand Prismatic Spring characterize the area.

Yellowstone is also an important wildlife refuge. Since the reintroduction of wolves in 1995, it has been considered a model project for nature conservation. The park attracts several million visitors annually and has been a UNESCO World Heritage Site since 1978.

Attribution: Dietmar Rabich / Wikimedia Commons / “Yellowstone National Park (WY, USA), Old Faithful Geyser – 2022 – 2599” / CC BY-SA 4.0