This group of 41 gorillas is Rwanda’s largest. This family is the hardest to trek as they tend to range high into the mountains. Originally studied by Dian Fossey, the Susa Group is the largest, with about 40 individuals, including 3 silverbacks. In the summer months in particular it can be a tough trek to reach this group high up on Mount Karisimbi, but its well worth the effort because of their number and because, uniquely, it has two sets of twins, a very rare occurrence in the world of gorillas.