Grand Geyser and Vent Geyser erupting in Yellowstone National Park
Grand Geyser erupts (right) with a simultaneous eruption from Vent Geyser (left). Grand Geyser is a fountain-type geyser reaching 200 feet in height and lasting up to 12 minutes. Grand Geyser is considered the tallest predictable geyser in the world, erupting about every 12 hours. It is often accompanied by bursts or eruptions from Vent Geyser and Turban Geyser just to its left. Upper Geyser Basin.