The Rift Valley lakes are a group of lakes in the East African Rift that runs north-south through the eastern side of the African continent, from Ethiopia in the north to Malawi in the south. These lakes include some of the oldest, largest, and deepest lakes in the world. Many are freshwater ecoregions of great biodiversity, while others are alkaline "soda lakes" supporting highly specialised organisms. The Rift Valley lakes are well known for the evolution of at least 800 cichlid fish species that live in their waters. More species are expected to be discovered.