High Quality Content by WIKIPEDIA articles! Ofu and Olosega are parts of a volcanic doublet in the Manu‘a Group of the Samoan Islands—part of American Samoa. The twin islands, formed from shield volcanoes, have a combined length of 6km. They are geographic volcanic remnants separated by the narrow 137m wide Asaga strait, a natural bridge of shallow coral reef. Before 1970, one had to wade between the two islands at low tide; now a single-lane road bridge over the strait connects villages on Ofu island with those on Olosega.