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
Endemism in the Hawaiian Islands was critical to the formulation of his theory of evolution is far exceeded in the more isolated Hawaiian Islands. The relatively short time that the existing main islands of the archipelago have been above the surface of the ocean (less than 10 million years) is only a fraction of time span over which biological colonization and evolution have occurred in the archipelago. High, volcanic islands have existed in the Pacific far longer, extending in a chain to the northwest; these once mountainous islands are now reduced to submerged banks and coral atolls. Midway Atoll, for example, formed as a volcanic