For many, Tiwai Island is Sierra Leone's natural gem: a patch of tropical rainforest of about 12 km² in the middle of the Moa River, with one of the highest concentrations of primates in the world. In this tiny space eleven monkey species live side by side —from the striking Diana monkey to the endangered western red colobus—, along with chimpanzees, the extremely rare pygmy hippopotamus and more than 135 bird species. Few places on the planet offer so much life in so little territory.
Tiwai (which means 'big island' in the Mende language) is not a park run from the top down: it is a community sanctuary, managed in partnership with the Mende villages on its banks, and it has pioneered primate research in West Africa since the 1980s. It survived the neglect of the civil war and re-emerged thanks to the joint work of the communities, Njala University and conservation organisations. In 2025 it crowned that story when UNESCO inscribed it, together with the Gola rainforest, as Sierra Leone's first World Heritage Site.
This guide explains how to visit Tiwai in depth: how to get there from Bo or Kenema, what admission and accommodation in tents inside the forest cost, which walks and canoe trips to do, how to maximise your chances of seeing primates and searching for the pygmy hippo at night, and why this small island has become a symbol of community-based conservation in Africa.
Tiwai began to gain scientific fame in 1982, when one of West Africa's first primate research stations was set up there. In 1987, at the request of researchers and of the Barri and Koya communities on its banks, the island was declared a wildlife sanctuary. The civil war (1991-2002) forced the station to be abandoned and the buildings fell into ruin, but after the peace the sanctuary was reborn thanks to the communities, Njala University and conservation NGOs. In 2025, together with Gola, Tiwai became Sierra Leone's first World Heritage Site.
Read the full history ↓The heart of the Mende people: Bo, the country's second city, the river rainforest of Tiwai and its primates, and the remote Turtle Islands, where time seems to stand still.
Read the history of The south and the coast →No exact prices: a scale from $ (budget) to $$$$$ (luxury), with 2-3 options per category.
Origins, formation and what the sources say.
In the Mende language, 'Tiwai' means 'big island', and that's exactly what it is: the largest of the river islands scattered along the Moa as it flows through southern Sierra Leone, about 12 km² of dry land covered in dense lowland tropical rainforest. The Moa, one of the country's great rivers, rises in the highlands of Guinea and runs down towards the Atlantic, wrapping around this island and protecting it with its waters.
Being an island is the key to Tiwai's extraordinary richness. Surrounded by water, it works as a natural refuge where wildlife, primates above all, reaches very high densities. The animals are packed into a small area that is fairly well sheltered from the hunting and deforestation hitting the mainland. Eleven species of daytime primates, plus nocturnal galagos and the very rare pygmy hippopotamus, share this tiny space.
Tiwai's forest belongs to the great Upper Guinean Forest biome, a belt of tropical rainforest that once stretched across West Africa from Guinea to Togo and is now reduced to threatened fragments. Tiwai is one of those precious fragments: an intact piece of an endangered ecosystem and a living laboratory of biodiversity.
Tiwai's modern history as a sanctuary begins in the 1980s. In 1982 a field research station opened on the island, one of the first in all of West Africa dedicated to studying primates. Drawn by that unique concentration of primates, national and international researchers working with universities began studying the ecology, behaviour and population dynamics of monkeys and other species.
The scientific work soon showed that Tiwai was a treasure of global importance, and people wanted to protect it formally. In 1987, at the joint request of the researchers and of the Barri and Koya communities living along the banks of the Moa, the island was declared a wildlife sanctuary. It was an early model of community-based conservation. Instead of a park imposed by the state, it was an agreement with the local villages, which gave up use of the island in exchange for a role in caring for it and a share in the benefits of research and early ecotourism.
In 1988 a management plan for the sanctuary was even completed. Everything suggested that Tiwai would become a beacon of African conservation. But Sierra Leone's history was about to take a tragic turn that would abruptly cut that flourishing short.
In 1991 Sierra Leone's civil war broke out. Fuelled by the diamond trade and led by the Revolutionary United Front (RUF), it was one of the most brutal conflicts in recent African history. The south and east of the country, exactly where Tiwai lies, were at the heart of the violence. Funding for the sanctuary was cut off, researchers and tourists could no longer reach it, and the research station was abandoned.
During the eleven years of war (until 2002), Tiwai's research buildings fell into ruin and were swallowed by the forest. The 1988 management plan was never put into practice. The riverside communities suffered displacement, fear and the poverty of war, and subsistence hunting put pressure on the wildlife. It seemed Tiwai's dream had died amid the undergrowth and the fighting.
And yet something survived. Because it was a natural refuge, the island kept much of its wildlife. Above all, the bond between the communities and their sanctuary survived, along with the memory of what Tiwai had been and could be again. When peace came in 2002, that bond would become the seed of its rebirth.
Once the war ended in 2002, Tiwai was gradually reborn through a joint effort by the Mende communities along the river, Njala University, the Government of Sierra Leone and national and international conservation organisations. Its sanctuary status was restored. A basic ecotourism infrastructure of tents, trails and a landing stage was rebuilt, and research started again, now led largely by students and scientists from Njala.
The new phase strengthened the community model. The neighbouring villages take part in managing the sanctuary, provide guides and boatmen, and receive a share of tourism income, so protecting the wildlife also brings economic benefits and local pride. Studies of primates, birds, amphibians and plants resumed, along with camera-trap monitoring, and Tiwai was back on the map for ecotourism and science.
This revival made Tiwai an internationally cited case study of community-based conservation after a war. It showed that when local communities are partners in conservation rather than adversaries, a sanctuary can survive even a war and flourish again. The small island in the Moa became a symbol of Sierra Leone's environmental resilience.
The crowning moment of this long story came in July 2025. At its 47th session, the UNESCO World Heritage Committee inscribed the 'Gola-Tiwai Complex' on the World Heritage List. It was a historic milestone: Sierra Leone's first World Heritage Site. The listing recognises the outstanding universal value of this complex, made up of Tiwai Island and the neighbouring Gola Rainforest National Park, both key remnants of the Upper Guinean forest.
The listing honours the complex's extraordinary biodiversity: Tiwai's primates, chimpanzees, the pygmy hippopotamus, the forest elephant and hundreds of bird species. It also honours the conservation model behind it, in which local communities play the leading role. For Sierra Leone, a country long associated with war and blood diamonds, the inscription was a source of national pride and a showcase for its nature.
Today Tiwai brings together the three layers of its history: the pioneering scientific sanctuary of the 1980s, the community project that rose from the ashes of war and the UNESCO site recognised by the world. For travellers, all this adds up to a rare and valuable experience. You walk through a forest full of monkeys on a small river island, knowing that every visit helps keep this marvel of biodiversity and human effort alive.
