Nyungwe covers around 1,000 square kilometres of hilly forest. Walking inside, the canopy is so thick that very little sunlight reaches the forest floor. The air is cool, damp and full of the sound of birds, insects and the swishing of leaves as monkeys move through the branches above your head.
Thirteen kinds of monkey live in Nyungwe. The most famous group is a giant troop of Angolan colobus monkeys with long black-and-white tails - sometimes 400 of them all travel together. From below, it looks like a black-and-white waterfall flowing across the treetops.
Nyungwe is also where two huge African rivers start. Water trickles down from the forest's springs and slowly grows into streams. Some of those streams eventually become part of the Congo River; others become part of the Nile River, which flows all the way to Egypt. One little drop of rain in Nyungwe could end up in the Mediterranean Sea.
High above the ground, a long suspension bridge stretches between the tallest trees - called the Canopy Walk. Visitors can walk along it, 60 metres above the forest floor, and see birds and monkeys at eye level. From up there, the forest looks like a sea of green ruffled by the wind.