Gravity would have a lot to do with it. the Mediteranean sea is a lot lower then the mountains in the south where the water comes from.
As with all rivers - Gravity.
The prevailing northerly winds in the Mediterranean Sea and the northward flow of the Nile River's current made it easier for boats to travel southward from Egypt towards regions in the south. This natural flow of wind and water facilitated trade by allowing vessels to travel more efficiently and economically.
The White Nile begins in rainforests at the edge of the savannah and goes northward through sahel and desert to meet with the Blue Nile. The Blue Nile starts in the Ethiopian Hill-Country before going northwest into desert where it meets with the Blue Nile. The two rivers join to create the Nile River, which continues uninterruptedly northward through desert.
It flows in Egypt. it flows northward though the eastern Sahara.
The River Nile is in Africa. It originates in Burundi, south of the equator, and flows northward through northeastern Africa, eventually flowing through Egypt and finally draining into the Mediterranean Sea.
Ocean currents like the Gulf Stream carry water from the tropics northward. These currents play a key role in redistributing heat and nutrients around the globe.
warm-water currents
In the Northern Hemisphere, ocean currents generally flow clockwise due to the Coriolis effect, which is caused by the Earth's rotation. This means that currents are deflected to the right in the Northern Hemisphere. For example, the Gulf Stream off the east coast of the United States flows northward and then eastward across the Atlantic Ocean.
River Nile
The two main rivers that feed into the Nile River are the White Nile and the Blue Nile. The White Nile originates from Lake Victoria and flows northward through Uganda and Sudan, while the Blue Nile begins at Lake Tana in Ethiopia and merges with the White Nile near Khartoum, Sudan. Together, they contribute to the Nile's flow, which is vital for agriculture and water supply in northeastern Africa.
The Nile river flows from south to north and no it is not the only river that goes northward. Other rivers that flow northward include the Red River (North Dakota), the Lena River (Russia), and the Shennandoah River (Virginia). +++ Most of the major Russian rivers flow North, because the Siberian Plain tilts very gently down to the North, and is fringed by mountains all along its Southern side.
Apart from fish and amphibians, sediment.