A trek deep into the Sumatran forest, precisely in the Gunung Leuser National Park, allowed me to have breathtaking encounters with these wonderful primates. Endemic to Indonesia, are these critically endangered Sumatran Orangutan, which I was lucky enough to observe a handful of times in their natural habitat. I got to see multiple Orangutan mothers with their mischievous babies throughout my trekking, unfortunately, no adult males showed up. Apart from the Orangutans were the elusive Thomas's langur, swinging about high in the forest canopy. More common but not less intriguing are the long-tailed macaques, moving in groups, always on the lookout for food.