The cataracts of the Nile are sections of the Nile river characterized by extreme shallowness and a number of obstacles that make them difficult to navigate. Historically, six sections of cataracts along the river have been particularly notable, and there are a number of smaller shallows that have come and gone with the Nile's changing terrain. Many people use these sections as a landmark when discussing the history of civilizations in Egypt, as the cataracts were well known to members of the ancient world.
Individuals can find the cataracts between Aswan in Egpyt and Khartoum in Sudan. Five of the six major sections are located in Sudan, with one in Egypt at Aswan. All of them are distributed along the so-called Great Bend, a section of the Nile where the river veers sharply off-course before turning back towards the Mediterranean. The Great Bend and the cataracts are caused by tectonic uplift, which pushes the Nile off-course along the Nubian Swell, an area of Africa that is extremely geological active.
Several things distinguish the cataracts of the Nile. The first is their shallowness. They are also studded with an assortment of rocks of various sizes, and the bottom of the river is extremely rough at the site. The area is also studded with small islets, and the water is often quite rough, making the cataracts seem like rapids. Although the word “cataracts” is derived from the Greek word for “waterfall,” the region is not, in fact, made up of waterfalls, although there are true ones along the route of the Nile.
The characteristics of the cataracts made them extremely difficult to navigate, and limited exploration and trade in that region of Africa for many civilizations. In order to travel over these shallows, people were forced to get out of their boats and drag them along the rocky riverbed, taking care to avoid protruding boulders and islets. In some cases, the cataracts became easier to navigate during the flood season, which elevated the water level.
People sometimes refer to various sections of the Nile along the Great Bend with the relevant cataract as a reference. For example, explorers referred to “traveling beyond the sixth cataract,” meaning that they were penetrating deep into Africa. Because the cataracts limited navigation, they also often marked the boundaries of various ancient civilizations as well.