The Nile is the longest river in the world and flows for 4,160 mi (6,695 km) through northeast Africa. The Nile originates near the equator and generally flows northward into the Mediterranean Sea. From its major source, Lake Victoria, in east central Africa, the White Nile flows through Uganda and into Sudan where it joins the Blue Nile at Khartoum. From the confluence of the White and Blue Nile Rivers, the Nile River continues to flow northwards into Egypt and on to the sea. The Nile Valley and the Nile Delta rank among the world's most fertile farming areas and are surrounded by a highly arid environment.