Volcanoes National Park, about an hour's drive east of Gisenyi, is one of the world's great wildlife experiences. The forested slopes of the Virunga volcanoes are home to several habituated gorilla families, and small groups of trekkers follow rangers up through the bamboo and hagenia forest to spend an hour with them. The trek can take anywhere from 30 minutes to four hours depending on where the gorillas have moved to overnight.
The park also offers golden monkey trekking (easier and much cheaper than gorilla permits), hikes to the active Bisoke crater lake, and a climb to the 4,507-metre summit of Mount Karisimbi for the very fit. Kigali-based agencies can arrange the permits and transport, but many visitors find it easier to stay in Gisenyi or at one of the lodges on the park boundary and arrange a driver there.