Steamboat Geyser in Yellowstone National Park’s Norris Geyser Basin is the world’s tallest active geyser, capable of major eruptions that hurl water more than 300 feet high from two vents, with the north vent reaching the greatest heights. It is especially notable for its extreme unpredictability: major eruptions have occurred as little as three days apart and as much as fifty years apart. After dormancy from 1911 to 1961, it set a yearly record with 29 eruptions in 1964, then entered a sustained active phase beginning in 2018, recording 48 eruptions in both 2019 and 2020. Its eruptions also affect nearby features such as Cistern Spring.