The five volcanoes in the park are called Karisimbi, Bisoke, Sabyinyo, Gahinga and Muhabura. Karisimbi is the tallest at 4,507 metres - higher than any mountain in Europe outside the Alps. Bisoke has a perfectly round crater lake on top that is sometimes shiny like a mirror.
The forests on the volcano slopes are damp, misty and full of bamboo. Bamboo is one of the favourite foods of the mountain gorillas. The gorillas spend their days walking slowly through the bamboo, eating, resting and playing in big family groups led by a huge silverback father.
The forest is also home to golden monkeys with bright orange fur, forest elephants you almost never see, and hundreds of kinds of bird. Buffalo and bushbuck wander through the trees. The volcanoes themselves are quiet - they have not erupted for thousands of years.
A scientist called Dian Fossey lived high on the slopes of the volcanoes from 1967 onwards. She studied the mountain gorillas every day for nearly 20 years, learning their names, their families and their personalities. Her work helped people understand that gorillas are gentle, family-loving animals, and that they needed protecting. Today the gorillas in the park are guarded by rangers who know each one by name.