Old Faithful in Yellowstone National Park Tour is often considered the world’s most famous geyser and its eruption schedule is highly predictable. The time between eruptions varies but since the year 2000, recorded intervals have ranged between 44 minutes and two hours.
Rather than watch Old Faithful from the crowded boardwalk, consider hiking the Observation Point Trail and watch it erupt from a viewpoint high above the entire geyser basin.