The Amazon River flows for more than 6,600 km, and with its hundreds of tributaries and streams contains the largest number of freshwater fish species in the world. Equally impressive are the unfathomable numbers of mammals, birds, amphibians, and reptiles4 found across the biome.

The Amazon River is a geographical marvel with several unique characteristics that set it apart from any other river on Earth. Most notably, it is the world's largest river by discharge volume; it carries more water than the next seven largest rivers combined and accounts for approximately 20% of the total river water that enters the world's oceans. During the wet season, parts of the river can exceed 120 miles in width, earning it the nickname "The River Sea." Unlike many other major rivers, the Amazon has no bridges crossing its entire 4,000-mile length, largely due to its vast width and the fact that most of its path through the rainforest lacks major roads. It also features the "Meeting of Waters" near Manaus, where the dark "blackwater" Rio Negro and the sandy-colored "whitewater" Rio Solimões flow side-by-side for several miles without mixing due to differences in temperature, speed, and density. Additionally, it is home to unique species like the pink river dolphin and the giant lily pad (Victoria amazonica).