a group of islands in the western Aleutian Islands archipelago (USA, state of Alaska). They consist of seven large islands (Kiska, Semisopochnoi, Amchitka, Little Sit-kin, Buldir, Rat, and Seguía) and several small islands. The islands are primarily mountainous (elevations to 1,221 m on Semisopochnoi Island). There are active volcanoes. A preserve for sea otter exists on Amchitka Island. The islands were discovered in the 18th century by Russian merchants and traders. The islands received their name because of the abundance of rodents on them at the time.