A breathtaking trip down Earth's longest river reveals its fabled past and complex, challenging present. Wild hippopotami, the mysteries of the deadly tsetse fly, the ancient Dinka and Shilluk African tribes and the Sudd- a swamp as large as England - are among the natural wonders encountered along the trek from Uganda to Khartoum to Egypt, before concluding at the manmade wonders of the Nile, the Jonglei Canal and the Aswan High Dam.