Gunung Leuser National Park is a large national park covering 950,000 hectares in northern Sumatra, Indonesia. Straddling the border of the provinces of North Sumatra and Aceh. One of the largest protected forested areas in southeast asia, Gunung Leuser National Park encompasses a range of environments from coastal lowland to volcanic peaks. Most Sumatran wildlife species are represented, though tigers, elephants and rhinos are in evidence mainly through mud tracks, trumpet calls and rustling bushes than actual sightings. The Alas river, which traverses much of the park?s length, is often the best vantage point for viewing the park?s flora and fauna. Ecologically sensitive river rafting operation are a good option for visitors, combining whitewater excitement with river-level views of forest life and just outside the park boundaries, daily activities at river settlements. The Bohorok wildlife research station and orangutan rehabilitation center lies at the park outskirts.

As a new destination, Tangkahan is an interesting alternative to Bukit Lawang. There is no orangutan rehabilitation center, but it is definitely more natural and far from as touristy as Bukit Lawang. The forests are still nice and have a rich wildlife including orangutan. The rivers are very clear and nice. The location is just on the border between palm oil plantation and the Gunung Leuser National Park. The accommodation is good but not yet used to tourists.

Bukit Lawang. A famous orangutan refuge/rehabilitation center, that suffered from major flooding on November 2, 2003, which killed many people and destroyed the village when waters raised up to 20 meters in places. The Indonesian government completed a new diversion channel and breakwater in July 2005, and temporary housing now exists for villagers (nice homes, but without running water). Villagers still bathe in the river that runs through the area. Free sightings are available just by sitting across from the sanctuary and waiting patiently; orangutans that have been rehabilitated and released often come back to the sanctuary from the wild to be fed. The sanctuary charges Rp.20,000 to see a couple orangutans it has in cages (for scheduled feedings), but if you walk around the grounds before 7:30AM or after 6:00PM, you can see these caged orangutans for free. Furthermore, if you want to walk into the jungle, they will request that you have a guide, so if you are travelling on a budget, a dry-season possibility is to hike for free along the river. You actually have a better chance of seeing monkeys and orangutans along the river that by trecking into the jungle, where sightings can't be guaranteed. However, be aware that several river crosses will be required as the river slightly shifts its course after every rainy season, so wear appropriate shoes. During the rainy season, such a trek is impossible and a boat is needed to cross over to the orangutan rehabilitation facility (rate Rp.500 per person for a 7 meter crossing). As at July 2007 it takes around 3-4 hours from Medan to Bukit Lawang due to the condition of the road (lots of potholes that have not been repaired due to lower tourist numbers visiting).