Volcanoes in Hawaii are formed by molten rock, ash, and gas that come out of Earth's crust. The most famous volcano in Hawaii is called Kilauea, which is located on the big island of Hawaii. When Kilauea erupts, it creates a fiery show of lava flowing down its sides and into the ocean. This creates new land and changes the shape of the island. Scientists closely monitor these volcanoes to make sure that people are safe.