The Great Rift Valley is a name given in the late 19th century by English explorer John Walter Gregory to the continuous geographic trough, approximately 3,700 miles iin length, that runs from northern Syria in Southwest Asia to central Mozambique in East Africa. In eastern Africa the valley divides into two, the Western Rift Valley and the Eastern Rift Valley.
The Western Rift, also called the Albertine Rift, is edged by some of the highest mountains in Africa, including the Virunga Mountains, Mitumba Mountains, and Ruwenzori Range. It contains the Rift Valley lakes, which include some of the deepest lakes in the world. Lake Victoria, the second largest freshwater lake in the world, is considered part of the Rift Valley system although it actually lies between the two branches. All of the African Great Lakes were formed as the result of the rift, and most lie within its rift valley.
In Kenya the valley is deepest to the north of Nairobi. As the lakes in the Eastern Rift have no outlet to the sea and tend to be shallow they have a high mineral content as the evaporation of water leaves the salts behind. For example, Lake Magadi has high concentrations of soda (sodium carbonate) and Lake Elmenteita, Lake Bogoria, and Lake Nakuru are all strongly alkaline, while the freshwater springs supplying Lake Naivasha are essential to support its current biological variety.
Since the Great Rift Valley covers portions of Kenya, Malawi and Tanzania, the types of activities available to you can be anything from day and night game drives in 4×4 vehicles to a dhow trip on Lake Tanganyika.