The measurement of the rivers is varies depending on the source and mouth of the rivers, so that is very difficult to calculate the exact length. The rivers lengths are given underestimations by some exploration till today. There are hundreds of rivers that exceed over 1000 km in length. Most of the longest rivers source are located in the middle of the regions or on the landscapes and many of the rivers taking birth from the high places such as the Himalayas, Rainforests. The Himalayas forms many rivers and outflow in Arabian and Bay of Bengal and Amazon is the largest rainforest in the world that created many rivers and outflow in the Atlantic Ocean. Commonly rivers that are formed by Swamps, Ephemeral Streams.
Some Brazilian and Peruvian analyzes have hinted that the Amazon is the World’s Longest River by its longest linking tidal canal and Adjacent Para estuary. The Nile River has been considered longer traditionally with total length covers 6,650, The Amazon river has length 6,400 km only 250 km shorter than Nile, Anyway the latest studies in the future can change the Longest River in the World. The Following Top 10 longest rivers in the world are by the data provided by the different sources.
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| Rank | Rivers Name | Length(km) | Drainage Basin | Outflow |
|---|---|---|---|---|
| 1 | Nile | 6,650 | Ethiopia, Eritrea, Sudan, Uganda, Tanzania, Kenya, Rwanda, Burundi, Egypt, Democratic Republic of the Congo, South Sudan | Mediterranean Sea |
| 2 | Amazon | 6,400 | Brazil, Peru, Bolivia, Colombia, Ecuador, Venezuela, Guyana | Atlantic Ocean |
| 3 | Yongtze | 6,300 | China | East China Sea |
| 4 | Missouri – Mississippi | 6,275 | United States, Canada | Gulf of Mexico |
| 5 | Yenisei | 5,539 | Russia, Mongolia | Kara Sea |
| 6 | Yellow River | 5,464 | China | Bohai Sea |
| 7 | Ob - Irtysh | 5,410 | Russia, Kazakhstan, China, Mongolia | Gulf of Ob |
| 8 | Parana | 4,880 | Brazil, Argentina, Paraguay, Bolivia, Uruguay | Rio de la Plata |
| 9 | Congo | 4,700 | Democratic Republic of the Congo, Central African Republic, Angola, Republic of the Congo, Tanzania, Cameroon, Zambia, Burundi, Rwanda | Atlantic Ocean |
| 10 | Amur | 4,444 | Russia, China, Mongolia | Sea of Okhotsk |