Some wildlife destinations announce themselves with dramatic safaris and crowds gathered around famous animals. Tiwai Island, in southeastern Sierra Leone, offers something altogether different. Here, the rainforest presses close to the banks of the Moa River, monkeys move through the canopy, and the possibility of spotting a rare pygmy hippopotamus gives every boat trip a sense of anticipation.
This small forested island is one of West Africa’s remarkable biodiversity hotspots, yet it remains relatively unfamiliar to international travellers. For those willing to venture beyond the continent’s better-known safari destinations, Tiwai offers an intimate encounter with a rainforest ecosystem that deserves far greater attention.
A Rainforest Island Hidden in the Moa River
Tiwai Island lies in Sierra Leone’s Southern Province, around 15 kilometres from the town of Potoru. Covering approximately 12 square kilometres, the island is surrounded by the Moa River and forms part of the Upper Guinean rainforest, one of the most biologically important forest regions in West Africa.
The first impression is often the sheer density of the vegetation. Towering trees create a layered green canopy, tangled roots line damp riverbanks, and the air carries the sounds of insects, birds and animals moving through the forest. This is not a landscape designed around easy wildlife viewing. Much of its life remains hidden, rewarding visitors who slow down and pay attention.
The island’s significance extends beyond its beauty. In 2025, UNESCO inscribed the wider Gola-Tiwai Complex on the World Heritage List, recognising its exceptional biodiversity and importance for threatened species. The complex includes Tiwai Island Wildlife Sanctuary and Gola Rainforest National Park, together protecting a crucial part of the remaining Upper Guinean forest.
The Elusive Pygmy Hippopotamus
For many visitors, the possibility of encountering a pygmy hippopotamus is one of Tiwai Island’s biggest attractions.
Much smaller than its familiar common relative, the pygmy hippopotamus is a shy, largely solitary mammal that inhabits forested environments in West Africa. It spends much of its time in or near water and is difficult to observe in the wild. Tiwai is recognised as an important stronghold for this threatened species, although a sighting is never guaranteed.
A guided boat trip along the Moa River offers a chance to look for signs of wildlife along the banks. The experience can be rewarding even when the hippos remain out of sight. A ripple in the water, a movement among the reeds or tracks along a muddy edge can hint at the animals living just beyond