Ta‘ū is the largest island in the Manu‘a Group and the easternmost volcanic island of the Samoan Islands. Ta‘ū is part of American Samoa. In the early 19th century, the island was sometimes called Opoun.
Administratively, the island is divided into three counties: Faleasao County, Fitiuta County, and Ta'u County. Along with Ofu and Olosega islands, Tau Island comprises the Manua District of American Samoa. The land area of Tau Island is 44.31 square kilometres (17.11 sq mi) and it had a population of 873 persons as of the 2000 census.