Saunders Island is a crescent-shaped island 8.5 by 5 kilometres long, lying between Candlemas Island and Montagu Island in the South Sandwich Islands, a British Overseas Territory in the southern Atlantic Ocean. It is a volcanic island composed of an active stratovolcano, 990-metre (3,248 ft) Mount Michael, and a cluster of pyroclastic cones on the southeastern side. Mount Michael has a lava lake in its summit crater, which is fumarolically active, and there is widespread evidence of recent eruptions across the island.

Montagu Island is the largest of the South Sandwich Islands, located in the Scotia Sea off the coast of Antarctica. It is almost entirely ice-covered with only sparse rocky outcrops, and consists of a large caldera with a large parasitic cone, Mount Oceanite. Several secondary volcanic cones have formed in the caldera, including Mount Belinda.