Mount Leuser National Park represents several ecosystem types, from coastal forest ecosystem through tropical lowland forest ecosystem to montane forest ecosystem. Most of Gunung Leuser National Park area is covered with thick Dipterocarpaceae forest with rivers and waterfalls flowing through it. There are some endangered and peculiar plants, namely daun payung raksasa (Johannesteijsmannia altifrons), rafflesia flowers (Rafflesia atjehensis and R. micropylora), and Rhizanthes zippelnii-the biggest flower, with a diameter of 1.5 metres. In addition, there is one plant unique to the area: the ara, a strangling plant.

Mount Leuser National Park has been declared a Biosphere Reserve. Under a cooperation program between Indonesia and Malaysia, the Park is also designated as a "Sister Park" to the Taman Negara in Malaysia.

Interesting locations/attractions Gunung Leuser National Park:

Gurah: fantastic views, valleys, waterfalls; animals and plants such as Rafflesia, orangutans, birds, snakes and butterflies.Bohorok: an orangutan rehabilitation centre; ecotourism activities like kayaking/canoeing, camping, and birdwatching.Kluet: boating on rivers and lakes, trekking through coastal forest and caving. Kluet is also a habitat of tigers.Sekundur: camping, caving, animal observation.Ketambe and Suak Belimbing: suitable place for research on primates and other animals; research facilities include accommodation and a library. Gunung (Mount) Leuser (3,404 m asl.) and Mt. Kemiri (3,314 m asl.): mountain climbing and hiking. River rafting along the Alas River: start from Gurah-Muara Situlen-Gelombang for a three-day trip.

Cultural attractions outside the Park include the Lake Toba Festival in June (held on the Lake) and the Malay Culture Festival held in July in Medan.

Declared : Minister of Agriculture, in 1980,a total area of 792,675 hectaresDesignated : Minister of Forestry, SK. No.276/Kpts-VI/1997,a total area of 1,094,692 hectaresLocation : Regencies Southeast Aceh, South Aceh,Aceh Singkil (Province of Nanggroe Aceh Darusslam), andRegency of Langkat (Province of North Sumatra)