The Nile River, the longest river in the world, is made up mostly of the Blue Nile and White Nile. The Blue Nile originates in Lake Tana in Ethiopia and the White Nile is said to originate in either Burundi or Rwanda, but neither has been entirely agreed upon. The Blue Nile and White Nile meet up at Khartoum, Sudan and the Nile ends at the Mediterranean Sea.