The 'Old Faithful' in Yellowstone National Park, Wyoming is a/an

The 'Old Faithful' in Yellowstone National Park, Wyoming is a Geyser. Old Faithful is a cone geyser located 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 receive a name. It is a highly predictable geothermal feature, and has erupted every 44 to 125 minutes since 2000.