Visitors to Hawaii Volcanoes National Park can explore a range of geological features. The park is home to two active volcanoes, Kilauea and Mauna Loa, both of which are open for exploration. Visitors can also view volcanic craters, steam vents, cinder cones, lava tubes and petroglyphs left by ancient Hawaiians. Other geological features that visitors may observe include coastal cliffs formed by the eruption of lava into the sea and an array of dramatic landforms created as a result of ongoing volcanic activity in the area.