Nouabalé-Ndoki National Park

Listen first. Before you see anything, the forest reaches you as sound. There is a steady hum of insects, a call from somewhere high in the canopy, and the drip of water falling leaf to leaf long after the rain has stopped. The air is warm and heavy, and it smells of wet earth and rotting fruit. Underfoot, the ground is soft and springy. You are standing in one of the least disturbed rainforests left in Central Africa.

This is Nouabalé-Ndoki National Park, in the far north of the Republic of the Congo. It covers roughly four thousand square kilometres of lowland forest, swamp and river. The park was created in 1993. Its name comes from two rivers, the Nouabalé and the Ndoki, which wind through it. There are no paved roads inside. People travel here by boat, by vehicle along forest tracks, and above all on foot.

Why has this forest stayed so intact? Part of the answer is geography. The land is remote, wet and difficult to cross. Swamps and rivers kept large-scale logging and hunting away for a long time. When scientists first surveyed this area in depth, they found animals that showed little fear of people. That surprised many researchers. In most forests, wild apes and elephants flee at the first sign of humans. Here, some simply watched.

The park does not stand alone. Today it forms part of the Sangha Trinational, a cross-border protected area shared with neighbouring parks in Cameroon and the Central African Republic. In 2012, UNESCO listed this trinational landscape as a World Heritage Site. That means three countries now protect one continuous forest. Animals do not recognise borders, so elephants and gorillas can move freely across the whole landscape.

The park is managed through a partnership between the Congolese government and the Wildlife Conservation Society, an international conservation group. Park headquarters sit at Bomassa, on the banks of the Sangha River. The river is wide and brown, and long wooden canoes called pirogues move along it slowly. For many visitors, Bomassa is the first stop. It is also the place where rangers, researchers and local staff begin their work each day.

Now, a word about the clearings. Scattered through the forest are open, marshy glades known locally as bais. They are rich in minerals, and animals come to them to drink, feed on water plants and take in salts from the soil. Mbeli Bai is the best known. From a wooden viewing platform at its edge, people have watched western lowland gorillas here for decades. It is one of the longest-running gorilla studies of its kind.

Sit quietly on that platform and the scene unfolds slowly. A silverback — the large adult male, named for the grey hair on his back — may step out of the trees first. Females and young follow. They wade into the shallow water and pull up plants. Forest elephants may arrive too, smaller than savannah elephants, with straighter tusks. Sometimes a sitatunga, a shy swamp antelope, moves through the reeds. Patience is the whole skill here.

Here is something many visitors do not expect. The forest elephants are gardeners. They eat large amounts of fruit and carry the seeds over long distances. When the seeds pass through, they land in fertile dung, ready to sprout. Several tree species depend heavily on elephants for this. So the shape of the forest around you is partly the work of these animals. Lose the elephants, and over time the forest itself would change.

Deeper in the park lies the Goualougo Triangle, an area of forest between rivers. Long-term research on chimpanzees has been carried out there. Scientists have recorded these chimpanzees using tools in careful, planned ways. They use different sticks for different tasks, for example to reach into termite mounds. The researchers describe this as a set of tools used in sequence. It is a reminder that culture and skill are not only human traits.

This forest is also a human landscape. The BaAka, an Indigenous forest people of the region, have lived in and around these forests for generations. Their knowledge of plants, animal tracks and forest paths is deep and practical. Many BaAka work with the park as trackers and guides. When a guide stops, bends down and points at a broken stem or a faint print, follow their eyes. They are reading the forest in real time.

The forest has its pressures. Poaching for ivory and bushmeat remains a serious threat across Central Africa. Logging concessions surround parts of the park. Rangers patrol the area, and conservation teams work with nearby communities and timber companies. Still, the long-term future of places like this is not guaranteed. Your visit, and the attention it brings, is part of what keeps this forest valued and protected.

As you move along a trail, look up. The canopy is layered, with tall emergent trees rising above the rest. Thick lianas — woody vines — hang down and loop between trunks. Light reaches the ground only in thin shafts. Butterflies gather on damp patches of soil. In the mud, you may notice the deep round prints of elephants, filled with water. Every detail here is alive and changing.

Before you leave, stand still for one more minute. Close your eyes if you can. Listen again to the insects, the birds and the distant water. Notice the warmth on your skin and the smell of the soil. This sound has carried through these trees for a very long time. As you walk back towards the river, take some of that quiet with you.