Sumatra is an island in western Indonesia, to the west of the Sunda Islands. It is the largest island that is entirely in Indonesia (two larger islands, Borneo and New Guinea, are shared between Indonesia and other countries) and the sixth largest island in the world at 473,481 km2 with a population of 50,365,538.
The Bukit Barisan mountain which contain several active volcanoes, form the backbone of the island, while the northeast sides are outlying lowlands with swamps, mangrove and complex river systems. The equator crosses the island at its center on West Sumatra and Riau provinces. The climate of the island is tropical, hot and humid with lush tropical rain forest originally dominating the landscape.
Sumatra has a huge range of plant and animal species but has lost almost 50% of its tropical rainforest in the last 35 years, and many species are Critically Endangered such as Sumatran Tiger, Sumatran Rhino and Sumatran Orangutan. (Copy from wikipeda.org)