The Nile River, the longest river in the world, flows from south to north through northeastern Africa. It begins in the rivers that flow into Lake Victoria (located in modern-day Kenya, Tanzania and Uganda) and travels more than 6,800 kilometers (4,000 miles) to the north, emptying into the Mediterranean Sea on Egypt’s coast. The river’s three main tributaries are the Atbara, the Blue Nile and the White Nile. The entire Nile River basin—made up of interconnected streams, lakes and rivers—threads its way through 11 African countries: Burundi, Democratic Republic of the Congo, Egypt, Eritrea, Ethiopia, Kenya, Rwanda, South Sudan, Sudan, Tanzania and Uganda.

The Nile River was critical to the development of ancient Egypt. The soil of the Nile River Delta between Cairo, Egypt and the Mediterranean Sea is rich in nutrients, due to the large silt deposits the Nile leaves behind as it flows into the sea. The banks of the Nile all along its vast length contain rich soil as well, thanks to annual flooding that deposits silt. From space, the contrast between the Nile's lush green river banks and the desert through which it flows is obvious.

For millennia, much of Egypt's food has been cultivated in the Nile Delta region. Ancient Egyptians developed irrigation methods to increase the amount of land they could use for crops to support a thriving population. Beans, cotton, flax and wheat were important, abundant crops that could be easily stored and traded.

The Nile River Delta was also an ideal growing location for the papyrus plant. Ancient Egyptians used the papyrus plant in many ways, such as making cloth, boxes and rope, but by far its most important use was in making paper. Besides using the river's natural resources for themselves and trading them with others, early Egyptians also used the river for bathing, drinking, recreation and transportation. Today, National Geographic Explorer Raghda (Didi) El-Behaedi studies how ancient societies responded to a shrinking water supply, particularly focusing on Lake Moeris and the Nile. Informed by technologies such as remote sensing and GIS, El-Behaedi seeks to better understand ancient landscapes and subsequently bolster cultural heritage preservation efforts in Egypt.

Today, 95 percent of Egyptians live within a few miles of the Nile. Canals bring water from the Nile to irrigate farms and support cities. The river's water is a vital resource for millions of people who depend on it for irrigation, drinking water, fishing and hydroelectric power. The river has served as an important transportation route for thousands of years. Today, some residents of Cairo have begun using private speed boats, water taxis or ferries to avoid crowded streets.

Dams, such as the Aswan Dam in Egypt, have been built to help to tame the river and provide a source of hydroelectric power. However, the silt and sediment that used to flow north, enriching the soil and building the delta, is now building up behind the dam. Instead of growing in size through the soil deposits, the delta is shrinking due to erosion along the Mediterranean Sea. In addition, annual flooding no longer occurs along parts of the Nile. These floods were necessary to flush and clean the water of human and agricultural waste. As a result, the water is becoming more polluted.

The many habitats in the Nile River basin support biodiversity in the region. The basin is home to a variety of animals, including the hippopotamus, the monitor lizard and the fearsome Nile crocodile. The Nile River Delta is also a vital winter stopover for millions of birds migrating along the East African flyway.

The rivers and lakes are filled with a variety of freshwater fish, including the sharp-toothed tigerfish and the Nile perch, a large fish that can grow to weigh more than 79 kilograms (175 pounds). Fishing is a way of life for many inhabitants of northeast Africa, who depend on it for food and a way to earn money. Today, however, the Nile River system is threatened by pollution, as it harms the fish and other wildlife that live in its aquatic environment. This pollution is also impacting the people who depend on the Nile for their drinking water and for irrigating their crops.

With so many countries sharing and relying on the interconnected water resource that is the Nile River basin, it is essential for them to cooperate in regard to its use. Unfortunately, these countries do not always agree on how to manage the water supply. One of the countries most impacted by pollution and water shortages is Egypt, which gets 90 percent of its water from the Nile. As the country’s population increases, experts say Egypt’s demand for water may soon exceed its supply. The United Nations predicts that Egypt will face a water shortage by 2025.

This need for cooperation led to the formation of the Nile Basin Initiative (NBI) in 1999. The NBI brings representatives from all 11 countries in the Nile River basin together to discuss ways to manage and share the water. In 2010, one NBI initiative saw four nations—Ethiopia, Rwanda, Tanzania and Uganda—enter into a Nile River water-sharing agreement. The agreement, called the Cooperative Framework Agreement, allows the countries to use the Nile River system in their borders to encourage cooperation and sustainability. Kenya and Burundi later signed onto the agreement, which remains in place today.

There are still disagreements over the management of the Nile's waters. Ethiopia recently built its own dam, the Grand Ethiopian Renaissance Dam, over the Blue Nile tributary. The Blue Nile supplies most of the water that flows into the Nile River. This has created conflict between Ethiopia and the two countries, Egypt and Sudan, that are downriver. Egypt and Sudan depend on the flow of water from the Blue Nile.

The dam, however, is a big benefit to Ethiopia. It will allow all of its citizens to have access to electricity. In 2015, the three "downriver" countries impacted by Ethiopia's dam—Egypt, Ethiopia and Sudan—signed an agreement to cooperate as the dam was built and its reservoir slowly filled. The Grand Ethiopian Renaissance Dam is now Africa's largest dam. It began producing electricity in 2022.