Unalaska 61 mi (98 km) SE Nikolski 76 mi (123 km) SW Akutan 93 mi (149 km) NE Saint George 194 mi (312 km) NW Anchorage 835 mi (1343 km) NE
Bogoslof Island is the largest of a cluster of small, low-lying islands comprising the emergent summit of a large submarine stratovolcano. This stratovolcano rises about 6000 ft (1800 m) from the Bering Sea floor, but is only about 300 ft (100 m) above sea level at its highest point . Bogoslof volcano is unusual in its location. It is slightly north of the main Aleutian volcanic front, and is interpreted as a back-arc feature. This volcano is frequently altered by both eruptions and erosion, and has undergone dramatic changes in historical time.
There are currently two islands of this volcano above sea level: Fire Island and Bogoslof Island. Fire Island lies about 2000 ft (610 m) northwest of Bogoslof and is a tiny sea stack. The current-day Fire Island is what remains of a volcano dome extruded in 1883. Bogoslof is triangular in shape, and about 1.2 mi (2 km) by 0.5 mi (0.75 km). On the southwest side of Bogoslof are steep-sided twin pinnacles called Castle Rock - this is what remains of a dome erupted in 1796. On the north end of Bogoslof Island is a small, 500 ft (150 m) by 900 ft (275 m) dome that was erupted in 1992. Other domes erupted at Bogoslof, (which has had confirmed eruptions in 1796-1804, 1806-1823, 1883-1895, 1906, 1907, 1909-1910, 1926-1928, and 1992) have been lost to explosions or erosion .