5. Sumatra
Population: 50,826,215
An elongated island, Sumatra is 1709 km long and is the 6th largest island in the world. Being a border of the Pacific Ring of Fire, Sumatra has a number of volcanoes, mostly located in the Great Sumatran fault which runs along the western portion of the whole island. The island is also the biggest producer of Indonesian coffee, producing mostly Arabica and Robusta beans.
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