encyclopedia The Zambezi (also spelled Zambeze and Zambesi) is the  fourth-longest   river  in  Africa , and the largest flowing into the  Indian Ocean  from Africa. The area of its  basin  is 1,390,000 square kilometres (540,000 sq mi), [1] [2]  slightly less than half that of the  Nile . The 3,540-kilometre-long river (2,200 mi) has its source in