The jagged, forested peaks of Piumfa and Sunuitao mountains loom over the 2- mile (3-km) stretch of coral sand on Ofu Island’s south coast. The offshore reef is home to 150 species of coral and 300 species of fish, but you’ll need to bring your own snorkeling equipment if you want to see them – there is little in the way of tourist infrastructure here.
Ofu and Olosega are parts of a volcanic doublet in the Manu‘a Island Group, which is 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 12 square kilometers (5 square miles).
Together, they have a population of about 500 people. Geographically, the islands are volcanic remnants separated by the narrow, 137-meter-wide (449-foot)) 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 491 m (1,611 ft). The highest peak on Olosega is Mount Piumafua, at 629 m (2,064 ft). The most recent volcanic eruption was in 1866, 3 km (1.9 mi) southeast of Olosega. Wikipedia