There are few places left on earth that might rightfully be called Eden, and the Mahale Mountains, on the edge of Lake Tanganyika in western Tanzania, is one of them. On a far-flung beach along the eastern shores of the lake, below a huge story-book tropical forest, is the tiny sanctuary of Greystoke Mahale. The water is as clear as gin, the air scented, and the livin ...g very easy indeed. The slopes of the Mahale Mountains rise behind camp, home to the world's largest known population of chimpanzees. Within hiking distance is one such group of 60. The forest itself is special, with eight other species of primate, shyer forest mammals, birds, butterflies, giant vines and waterfalls.