Morning sunlight illuminates the southeast-facing slopes of the Islands of the Four Mountains. The islands, part of the Aleutian Island chain, are actually the upper slopes of volcanoes rising from the sea floor: (from left to right) Herbert, Carlisle, Cleveland, and Tana. Carlisle and Herbert volcanoes are distinct cones and form separate islands. Cleveland volcano and the Tana volcanic complex form the eastern and western ends respectively of Chuginadak Island. Cleveland volcano is one of the most active in the Aleutian chain, with its most recent activity-eruptions and lava flow emplacement-taking place in May of 2013. Carlisle volcano, had its last confirmed eruption occurred in 1828, with unconfirmed reports of activity in 1987. Herbert volcano displays a classic cone structure breached by a two-kilometer wide summit caldera, but there are no historical records of volcanic activity. The easternmost peak, Tana is a volcanic complex comprised of two east-west trending volcanoes and associated younger cinder cones. Image was taken by the Expedition 38 crew on the ISS.