The largest islands in the group are, from west to east, Kiska, Little Kiska, Segula, Rat or Kryssei, Khvostof, Davidof, Little Sitkin, Amchitka, and Semisopochnoi. The total land area of the Rat Islands is 934.594 km² (360.849 sq mi). None of the islands are inhabited.
The Rat Islands are very earthquake-prone as they are located on the boundary of the Pacific and North American tectonic plates. In 1965, there was a major earthquake with the magnitude 8.7 in the Rat Islands.