Located within the Bransfield Strait, the island is roughly circular and horseshoe-shaped, with a maximum diameter around . The highest peak, Mont Pond on the east side of the island, has an elevation of , while Mount Kirkwood on the west has an elevation of . Over half (57%) of the island is covered by glaciers up to 100 m thick, ice-cored moraines, or ice covered pyroclasts. The centre of the island has been flooded by the sea to form a large bay, now called Port Foster, about long and wide. The bay has a narrow entrance, just wide, called Neptune's Bellows. The port is a basin with a flat floor up to 170 m deep with several small submarine cones and domes. The port is rimmed by a shallow coastal shelf with sandy-gravelly beaches. The outer coast of the island is characterized by cliffs of rock or ice.