Volcanoes are mountains with deep holes that go into the Earth. There are three types of volcanoes: active volcanoes that can erupt, dormant volcanoes that are currently sleeping, and extinct volcanoes that cannot erupt again. Examples provided are Kilauea as the most active volcano in Hawaii, Mount Fuji in Japan being dormant, and Anatahan being an extinct volcano in the Pacific Ocean. Underwater volcanoes can form islands as they erupt, such as the Galapagos Islands near Ecuador which were formed underwater and include 13 big islands and 6 smaller islands, with some still experiencing eruptions. Mount Tambora in Indonesia erupted in 1815 killing over 3,600 people and