Gorilla trekking is the region's unrivalled main attraction and the Volcanoes National Park is where to go in Rwanda to do it. Its mountainous terrain and dense forests make for tough walking conditions but the rewards are matchless: butterflies, birds and primates, headlined of course by families of habituated mountain gorillas.
Volcanoes National Park is the site of primatologist Dian Fossey's Karisoke Research Station, where she led a team to study gorillas in the wild. You can undertake about a 2-hour hike to her tomb, which is - like so much in Rwanda - both moving and inspiring. The hike is good time to look out for primates, hogs, forest elephants and a plethora of bird species.
There are a few troops of habituated golden monkeys, whose antics are great fun to watch. Golden monkeys are also endangered and permits are required for trekking them.
It is always worth understanding more about the indigenous culture of the area you are visiting. Take a guided community walk to Iby'Iwacu village where you can experience traditional dancing, discover beer brewed from bananas, and visit a local healer.
Serious hikers might want to consider a 2-day trek to Mount Karisimbi. Although this is fairly strenuous, you will be rewarded with excellent birding, spectacular scenery and the summit of the fifth highest mountain in Africa.