The second-longest river in the world is the Amazon River. It is generally considered second only to the Nile River in length, with the Nile being the longest. The Amazon River's length is approximately 6,400 to 6,575 kilometers (about 4,000 to 4,086 miles), depending on measurement methods and source definitions, while the Nile is about 6,650 kilometers (4,130 miles) long

. The Amazon River flows through South America, originating in the Andes Mountains of Peru and passing through countries including Peru, Bolivia, Venezuela, Colombia, Ecuador, and Brazil before emptying into the Atlantic Ocean

. It is also the largest river by discharge volume in the world. In summary:

• Longest river: Nile River (~6,650 km)
• Second-longest river: Amazon River (~6,400–6,575 km)

This ranking is widely accepted despite some debate over exact lengths due to measurement variations