Mokele-mbembe: Congo's version of the Loch Ness Monster?
People in the far north of Congo-Brazzaville have long reported sightings of a large, mysterious long-necked creature, swimming in the rivers and lakes of the rainforest.
Over 50 expeditions have been launched to try to find evidence of the creature, known as the Mokele-mbembe.
None have come back with any scientific evidence, and most scientists remain sceptical about its existence.
But others remain hopeful. Adam Davies is a British civil servant who spends his spare time and money travelling the world in search of creatures as yet unknown to science. He explains why he went to Congo.
Archive footage: Spirits of the Forest, BBC
27 Dec 2011