Rivers

A river is a natural stream of fresh water flowing across the land from a high place down to a lower one, usually ending in a lake, another river, or the sea. Rivers are the planet's arteries: they carve canyons, water farmland, support most major cities, and carry tiny bits of every mountain they pass slowly down to the ocean.

  • Longest RiverNile6,650 km, Africa
  • Largest by VolumeAmazonmore water than the next 7 combined
  • Most CountriesDanube10 countries, all in Europe
  • Number of Major RiversHundredswith countless tributaries
  • Where Rivers StartMountainsor springs, lakes, melting glaciers
  • Where Rivers EndThe Seausually via a mouth or delta

How long are the famous rivers?

Length in kilometres:

Length (km)
Nile6,650
Amazon6,400
Yangtze6,300
Mississ.6,275
Danube2,860
Thames346

The Nile and the Amazon are so close in length that experts still argue about which is actually longer. Both are roughly 19 times the length of the Thames.

What is a river?

A river is a stream of fresh water flowing in a more-or-less permanent channel. The place where a river starts is called its source (often a spring, melting glacier, or small lake high in the mountains). The water it gathers along the way is called its catchment. The point where it ends is called its mouth.

How rivers form

Rivers start when rain or melting snow runs downhill. As small trickles join up they form streams; streams join up to form rivers; rivers join up to form bigger rivers. The smaller waterways that feed a river are called its tributaries. Over thousands of years, the moving water carves valleys, canyons, and gorges out of solid rock. The Grand Canyon was carved by the Colorado River.

FactThe Amazon River carries about a fifth of all the river water on Earth. So much fresh water pours out of its mouth that the Atlantic Ocean is less salty for around 160 km offshore.

Wildlife of rivers

Rivers are full of life. Fish like salmon, trout, pike and carp live their whole lives in or around rivers. Otters, beavers, hippos, river dolphins, and crocodiles all rely on rivers. Many birds (kingfishers, herons, dippers) hunt along the banks. Even the very largest river, the Amazon, has its own kind of pink river dolphin.

Rivers and people

Almost every great city in history grew up next to a river. The Nile fed ancient Egypt. The Thames built London. The Tigris and Euphrates cradled the first civilisations of Mesopotamia. Rivers gave people fresh water to drink, fish to eat, transport for trade, soil that flooded fertile, and a barrier against enemies. Today most countries still get most of their drinking water from rivers.

Did you know?Every drop of fresh water in every river was once rain that fell from a cloud. The water cycle keeps moving the same water round and round between sea, sky and land, so you may have drunk water that a dinosaur once drank.
Deeper dive: the three stages of a river

Most rivers go through three stages on their way from source to sea.

  • Upper course (mountains): steep, narrow, fast-flowing. Lots of small waterfalls and rapids. The river is busy cutting down through rock.
  • Middle course (hills and lowland): the river slows down and starts to wind in big loops called meanders. Tributaries join in.
  • Lower course (close to the sea): wide, deep, slow. The river drops the sand and mud it has been carrying, building wide plains and sometimes a fan-shaped delta where it meets the sea.

Pick a river below to read its fact file.

The NileThe longest river in the world, flowing about 6,650 km from East Africa to the Mediterranean and feeding ancient Egypt.
The Amazon RiverThe largest river on Earth by water volume, draining nearly half of South America and carrying more water than the next seven biggest rivers combined.
The YangtzeThe longest river in Asia and the third-longest in the world, flowing across China to the East China Sea.
The MississippiThe main river of the United States, flowing south from Minnesota to the Gulf of Mexico through ten states.
The DanubeEurope's second-longest river, flowing through ten countries and four capital cities on its way to the Black Sea.
The GangesA sacred river in northern India and Bangladesh, fed by Himalayan glaciers and home to over 400 million people along its banks.
The ThamesThe river running through London, England. Once heavily polluted, now home again to seals, otters and over 100 fish species.
The MekongA huge river running through six Southeast Asian countries from China's Tibetan plateau to the South China Sea.
The VolgaThe longest river in Europe, flowing entirely within Russia for nearly 3,700 km from Moscow's northwest down to the Caspian Sea.
The NigerWest Africa's main river, taking a curious boomerang-shaped path from the highlands of Guinea round to the Gulf of Guinea.