It is an active volcano in the South Shetland Islands, off the Antarctic Peninsula. Its unique landscape comprises barren volcanic slopes, steaming beaches and ash-layered glaciers. It has a distinctive horse-shoe shape with a large flooded caldera. This opens to the sea through a narrow channel at Neptunes Bellows, forming a natural sheltered harbour. It is one of the only places in the world where vessels can sail directly into the centre of a restless volcano.