Astronauts say it is the most significant physical detail on the planet that is visible from space.The Rift is known for its spectacular scenery and abundant, sometimes unique, wildlife. A series of some thirty lakes lies along its length; the three largest in Africa are known as the Great Lakes and include Lake Tanganyika, the second deepest lake in the world, and Lake Victoria, the second-largest freshwater lake by surface area in the world. Some of the oldest remains of ancestral humans have been found in in the African segment of the valley.