The Amazon River is located in northern South America. It is the river with the largest drainage area and the largest flow in the world. It originates from the eastern slope of the Cordillera Mountains in the Andes Mountains in Peru. It has two sources: one is the Maranon River (usually regarded as the main source of the Amazon River), which originates from the high mountains of the Andes Mountains in Peru; the other is the Ucayali River, whose source is called the Apunmac River. The Maranon River and the Ucayali River merge near Nauta in Peru after passing through the mountains. The main and tributary rivers of the Amazon River meander through seven countries in South America. The Amazon River is called the Solimoes River from Iquitos in Peru to Manaus in Brazil, and the section from the mouth of the Rio Negro to the Atlantic Ocean is called the Amazon River. The Amazon River flows eastward across the northern part of Brazil and flows into the Atlantic Ocean near Marajo Island.

The Amazon River Basin starts from the source of the Madeira River in southern Bolivia (about 20°S) in the north of Branco, Brazil, and the source of the Paute River in Cuenca, Ecuador (79°31′W) in the west, and ends at the Marajo Bay in Brazil (about 48°W) in the east. The entire basin spans 25° latitude and 31°30′ longitude, with a drainage area of ​​6.915 million km2, accounting for about 39% of the entire area of ​​South America. The Amazon Plain, which the main stream crosses, covers an area of ​​5.6 million km2, which is the largest plain in the world. If the Amazon River is sourced from the Marañón River, the total length is 6,299 km, and if it is sourced from the Ucayali River, the total length is 6,436 km, second only to the Nile River, ranking second in the world. The average annual flow at the estuary is 175,000 m3/s, the average annual runoff is 693 billion m3, the average annual runoff depth is 1200 mm, the suspended sediment content is 0.22 kg/m3, and the sediment transport is 900 million tons. In the flood year, the river is 5 km wide near Manaus in the middle reaches, 20 km wide in the lower reaches, and 80 km wide at the estuary. The estuary is a trumpet-shaped bay with a width of 240 km. The average depth of the downstream river channel is 20-50 m, the maximum water depth is 100 m, and the annual water level fluctuation is 9 m. The average annual flow in Iquitos upstream is 20420-28200 m3/s. From Iquitos to the mouth of the Amazon River, the average slope is 0.035 m/km.