There are four types of volcanoes: active, dormant, extinct, and undersea. Active volcanoes such as Kilauea in Hawaii and Arenal in Costa Rica still erupt, while dormant volcanoes like Mount Fuji in Japan have not erupted in hundreds of years but could again. Extinct volcanoes like Vesuvius in Italy cannot erupt again. Undersea volcanoes can create new islands, like the Galapagos Islands off Ecuador's coast which were formed underwater and still experience eruptions.