The Blue Nile is one of the main tributaries of the River Nile. Both the Blue Nile and the White Nile form what is known as Nile near Khartoum. The Blue Nile starts at Lake Tana in Ethiopia and flows through Ethiopia and Sudan. It supplies about 60 percent of the water of the Nile. Even though it has more water than the White Nile, it is seen as the biggest tributary of the Nile.