Sumatra is the world’s sixth-largest island and the second-largest Indonesian island, after Borneo. 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 (not including adjacent islands such as the Riau Islands and Bangka Belitung Islands).
Sumatra supports a wide range of vegetation types which are home to a rich variety of species, including 17 endemic genera of plants. Unique species include the Sumatran pine which dominates the Sumatran tropical pine forests of the higher mountainsides in the north of the island and rainforest plants such as Rafflesia arnoldii (the world's largest individual flower), and the titan arum (the world's largest unbranched inflorescence).
The island includes more than 10 national parks, including 3 which are listed as the Tropical Rainforest Heritage of Sumatra World Heritage Site – Gunung Leuser National Park, Kerinci Seblat National Park and Bukit Barisan Selatan National Park. The Berbak National Park is one of three national parks in Indonesia listed as a wetland of international importance under the Ramsar Convention.