A caldera is a large, basin-shaped volcanic depression, typically formed by the collapse of a volcano into its emptied magma chamber. It is usually circular or elliptical in shape and can range in size from several kilometers to tens of kilometers in diameter. Calderas often have steep, inward-sloping walls and may be filled with water or contain a central lava dome or resurgent dome. Famous examples of calderas include the Yellowstone Caldera in the United States and the Santorini Caldera in Greece.
