Augustine Island (ô´gəstēn, –tĬn; ôgŭs´tĬn), unihabited volcanic island, S Alaska, in Kamishak Bay at mouth of Cook Inlet. The active Augustine (or St. Augustine) volcano, which forms the entire island, rises to 4,134 ft (1,260 m); ash from its last major eruption (1986) reached Anchorage, some 180 mi (290 km) to the northeast. The 1883 eruption is believed to have caused a 30-ft (9-m) tsunami locally.

Augustine, volcano, Alaska: see Augustine Island.