Tatsumaki Jigoku is one of Beppu Jigoku tour. It is also the only one where you can observe powerful geyser. A geyser is hot spring water in the ground that has been heated up by magma and thus is ejected vigorously from the ground. A geyser periodically spews water from the ground when it can no longer withstand the pressure that has been built up over time, and Tatsumaki Jigoku spews out water around every 30-40 minutes. The geyser is surrounded by rocks for safety, but it has the potential to spew up to a height of 50 meters.