sumatra, known also as "sumatera", is the sixth largest island in the world. it is in western indonesia. it is to the west of the sunda islands, and is bordered by the indian ocean. sumatra contains the provinces of daerah istimewa aceh, riau, riau islands, bangka belitung islands, jambi, bengkulu, lampung, north sumatra, south sumatra, and west sumatra. sumatra has an area of about 443,066 km². it is about long, and wide, at its widest point. in 2010, about 50 million people lived on sumatra.