Samoan Islands with black sand beaches. The highest peak is Mt. Silisili, on the island of Savai'i, one of the highest peaks in Polynesia at . The highest point in American Samoa is on Ta’u, Lata Mountain, at . The two large islands of Upolu and Savai'i in Samoa, are among the largest of Polynesian islands, at and , respectively, exceeded in size only by the two main islands of Fiji and the Hawaiian islands of Hawaiʻi and Maui. The island of Upolu is more populated than Savai'i. The next largest island is Tutuila, where the city and harbor Pago Pago (population
Hawaiian Islands southeastern island, Hawaii, and on the submerged but growing volcano to the extreme southeast, Loihi. The Hawaiian Volcano Observatory of the USGS documents recent volcanic activity and provides images and interpretations of the volcanism. Kīlauea has been erupting nearly continuously since 1983. Almost all of the magma of the hotspot has the composition of basalt, and so the Hawaiian volcanoes are composed almost entirely of this igneous rock. There is very little coarser-grained gabbro and diabase. Nephelinite is exposed on the islands but is extremely rare. The majority of eruptions in Hawaii are Hawaiian-type eruptions because basaltic magma is relatively