American Samoa, unorganised territory of the United States, formed by a group of seven islands in the southern Pacific Ocean, comprising Tutuila, on which a US naval station is located; the Manua group, consisting of Tau, Olosega, and Ofu; Aunuu; Rose Island; and Swains Island. Privately owned Swains Island and uncolonised Rose Island are coral atolls; the other islands are mountainous and of volcanic formation.