The major river that runs through the Amazon rainforest is the Amazon River. Stretching approximately 4,345 miles (7,062 kilometers), it is one of the longest rivers in the world. The Amazon River is a critical component of the rainforest ecosystem, supporting an incredible diversity of flora and fauna. It serves as a vital waterway for transportation and sustains the livelihoods of many indigenous communities. Its basin holds about one-tenth of all known species on Earth, making it essential for global biodiversity and environmental health.