I visited this WHS in September 2018 spending 4 nights in and about the Gunung Leuser National Park in Sumatra Island. After a long and bumpy ride from Medan Airport to Bukit Lawang (and a cheap overnight stay), we left for three days to explore the tropical rainforest of Gunung Leuser NP, camping at different places within the inscribed NP.

Our main goal was to admire the Sumatran Orangutans in the wild and we got to see more than a dozen including alpha males, females, young as well as newly born orangutans. The orangutan sanctuary was closed down and the few orangutans kept there were released as the number of orangutans grew enough over the years. We were lucky to spot a female orangutan with her baby around sunset just before she prepared their night nest high up in the trees just above our camping site. Early in the morning, they played together at the small waterfall nearby while we had breakfast which was an unforgettable moment.

Apart from the orangutans we also spotted several white handed gibbons, black gibbons, long-tailed macaques, pig-tailed macaques, Thomas' leaf monkeys, silvery lutungs, Sunda slow loris, monitor lizards, jungle peafowls, Salvadori's pheasants, Roll's partridges, Sumatran Laughingthrushes, Sunda Laughingthrushes, Rueck’s Blue-Flycatcher and countless butterflies.

Even though the Gunung Leuser NP's size is mindboggling (almost 8000km2), our nature guide was very knowledgeable in tracking and spotting different fauna species (mostly monkeys and primates) but also sun bear claw marks on different trees. Even though it was sunny during our visit, it can get very dark the more you venture inside the tropical rainforest. Luckily we didn't see any Sumatran tigers or leopard cats, nor did we see Sumatran elephants which can be easily seen by adding another day of trekking towards a deeper water source within the NP.

Sleeping in the tropical rainforest/jungle was a nightmare, not only because of the close encounters with large venomous spiders, all sorts of creepy crawlers (most impressive of which were the giant ants), a curious baby monitor lizard trying to enter our camp and last but not least noisy long-tailed macaques jumping on our tents. Nevertheless, it was well worth it. The Gunung Leuser National Park is also famous for being the home of the Rafflesia, the biggest flower in the world, as well as the home of the Amorphophallus titanium, the tallest flower in the world.

There were rather scary parts to climb up or down the tropical rainforest, so not only sturdy shoes are a must but ideally also walking sticks can be of great help. As of this year there is also a tree top walk just after the NP entrance with the UNESCO logo. At Bukit Lawang there is a tiny visitor centre which is more of an entrance ticket booth but worth visiting for the information boards if you have the time. After three days, we ended our visit with a very fun tubing experience down the river and back to Bukit Lawang.