The largest river in South America is the Amazon River. It spans approximately 4,345 miles (7,062 kilometers) and flows through several countries including Brazil, Peru, and Colombia. The Amazon basin is known for its vast rainforests and incredible biodiversity, making it one of the most vital ecosystems on the planet. The river not only serves as a crucial waterway for transportation and fishing but also plays a significant role in the global climate by acting as a carbon sink. Its size and importance have earned it recognition as one of the world's greatest natural wonders.