Bwindi

Declared in 1991, its local name means impenetrable, or dark, forest — a literal description of vegetation over 25,000 years old and so dense that it is one of the oldest and most ecologically stable forest ecosystems in East Africa, having come through the glacial cycles that swept away much of the surrounding woodland. It holds close to half the world's mountain gorillas, some 1,000 animals shared between Bwindi and the neighbouring Virunga massif. Each gorilla family has to go through a habituation process of two to three years, during which rangers and trackers visit them daily until the animals lose their fear of people — a necessary step before the regulated gorilla-watching tourism that now funds much of the park's conservation can be allowed.