Mismi is a 5,597-metre (18,363 ft) mountain peak of volcanic origin in the Chila mountain range in the Andes of Peru. A glacial stream on the Mismi was identified as the most distant source of the Amazon River in 1996; this finding was confirmed in 2001 and again in 2007. This claim has been challenged with three locations for the source of the Amazon identified, depending upon the definition of "source." The waters from Mismi flow into the streams Carhuasanta and Apachita, which flow into the Apurímac River. It is a tributary of the Ucayali which later joins the Marañón to form the Amazon proper.

The Amazon River in South America is the largest river by discharge volume of water in the world, and the longest or second-longest river system in the world, a title which is disputed with the Nile.