Volcano Islands, Jap. Kazan-retto, island group, c.11 sq mi (30 sq km), W Pacific. The group consists of three islands, of which Iwo Jima (Iwo To) is the most important. The highest peak (3,181 ft/970 m) is on Minami-iwo-jima. There are sugarcane plantations and sulfur mines on the Volcano Islands. The inhabitants are Japanese and Koreans. Japanese fishermen and sulfur miners arrived in 1887, and Japan annexed the islands in 1891. Captured by U.S. forces in World War II, the islands were placed under U.S. administration from 1945 until 1968, when they were restored to Japan.