Old Faithful is a cone geyser and was named in 1870 during the Washburn-Langford-Doane Expedition. It was the first geyser in the park to receive a name. It is also called the most predictable geographical feature on Earth erupting almost every 91 minutes.
Luckily we just arrived in time to see it go off after a hard days snowmobiling.
Yellowstone National Park.