Old Faithful is one of the most famous geysers in the world and is known for its predictability, erupting approximately every 91 minutes. Old Faithful was named by explorers in the 19th century for its consistent eruptions, which they found to be "faithful" in timing. The eruptions of Old Faithful typically last between 1.5 and 5 minutes, with an average height of around 130 feet, although some eruptions can reach up to 185 feet high. The geyser's water temperature can exceed 200 degrees Fahrenheit, and the steam and spray from an eruption can be visible from miles away.