Old Faithful is a cone geyser located in Yellowstone National Park that was first documented by the Langford-Washburn-Doane Expedition in 1870, making it the first geyser discovered in the park. It erupts every 44 minutes to 2 hours, shooting water up to 184 feet high, and has become one of Yellowstone's most famous geothermal features, drawing many visitors to its regular eruptions.