A volcanic island is formed by volcanic activity, where magma from beneath the Earth's crust erupts through the surface. Over time, repeated eruptions build up layers of lava and ash, creating land above sea level. These islands can vary in size and shape, often featuring steep cliffs and unique geological formations. Many volcanic islands are located along tectonic plate boundaries, where the Earth's plates interact. Examples include the Hawaiian Islands, formed by the Hawaiian hotspot, and the Galápagos Islands, which were created by volcanic activity along the Nazca Plate. These islands often host diverse ecosystems and unique wildlife.