Gunung Leuser National Park is a national park covering 7,927 km² in northern Sumatra, Indonesia, straddling the border of North Sumatra and Aceh provinces. The national park, named after Mount Leuser (3,381 m), protects a wide range of ecosystems. An orangutan sanctuary of Bukit Lawang is located inside the park. Together with Bukit Barisan Selatan and Kerinci Seblat national parks it forms a World Heritage Site, Tropical Rainforest Heritage of Sumatra.
Gunung Leuser National Park is 150 km long, over 100 km wide and is mostly mountainous. 40% of the park, which is mainly in the north, is steep, and over 1,500 m. 12% of the park only, in the lower southern half, is below 600 metres but for 25 km runs down the coast. 11 peaks are over 2,700 m and the highest point is Gunung Leuser, which 3,466 m high.
Gunung Leuser National Park is one of the two remaining habitats for Sumatran Orangutans (Pongo abelii). In 1971, Herman Rijksen established the Ketambe Research Station, a specially designated research area for the orangutan. Other mammals found in the park are the Sumatran elephant, Sumatran tiger, Sumatran rhinoceros, siamang, mainland serow, sambar deer and leopard cat.
After researchers put 28 camera-traps in July 2011, 6 months later the researchers found one male and six females and predicted the population is not more than 27 Sumatran rhinos which total population predicted is around 200 in Sumatra and Malaysia, a half population of 15 years ago.
Low-impact eco-tourism can be one of the most important sustainable, non-consumptive uses of Leuser, thereby giving local communities powerful incentives for conservation. Given the opportunities to view wildlife such as orang-utans, some experts view eco-tourism as a major potential source of revenue for communities living around Leuser (van Schaik, 1999).