What is the longest river in the world?

The longest river in the world is the Nile River, located in Africa. From its source in the country of Burundi to its mouth on the Mediterranean Sea, it extends for 4,145 miles (6,670 kilometers). But the world's second longest river, the Amazon (4,007 miles, or 6,451 kilometers), which is located in South America, is really the world's biggest river. It has more than 1,000 tributaries, or branches, and carries far more water than the Nile.