Ofu-Olosega

Ofu and Olosega are parts of a volcanic doublet in the Manuʻa Islands, which is a part of American Samoa in the Samoan Islands. These twin islands, formed from shield volcanoes, have a combined length of 6 km and a combined area of . Together, they have a population of about 500 people. Geographically, the islands are volcanic remnants separated by the narrow, Āsaga Strait, composed of shallow-water coral reef. Before 1970, people crossed between the two islands by waiting until low tide and then wading across the shallow water of the strait. Since 1970, there has been a bridge over the strait, providing a single-lane road that connects the two islands.

The highest peak on Ofu Island is Mount Tumutumu (also called Tumu), at . The highest peak on Olosega is Mount Piumafua, at . The most recent volcanic eruption was in 1866, southeast of Olosega.