Location:  Amazon river, northern South America, largely in Brazil, ranked as the largest in the world in terms of watershed area.

Description:

In Brazil the width of the river ranges between 1.6 and 10 km (1 and 6 mi) at low stage but expands to 48 km (30 mi) or more during the annual floods; the rate of flow ranges between 2.4 and 8 km/hr (1.5 and 5 mph); and the crest of the water at flood time often rises 15 m (50 ft) above the norm. To drain the vast mass of water, the Amazon has carved a deep bed in the plain through which it flows. In one sector near Óbidos, Brazil, the bed is more than 91 m (300 ft) below the average surface level of its water.

Because of its vastness, annual floods, and navigability, the Amazon is often called the Ocean River.

The Amazon enters the Atlantic through a broad estuary, roughly estimated at 240 km (about 150 mi) in width. Here delta deposits have formed a maze of islands that separate the river into branches.

The Amazon watershed includes the largest and wettest tropical plain in the world. Heavy rains drench much of the densely forested lowland region throughout the year but especially between January and June. Seasonal variation in rainfall is reflected by the width, rate of flow, and discharge volume of the river. During the months of maximum precipitation, broad areas traversed by the Amazon are subject to severe floods.

 Interesting Facts:

The Amazon proper is navigable to ocean liners of virtually any tonnage for two-thirds of its course. Transatlantic ships call regularly at Manaus, nearly 1600 km (1000 mi) upstream; and ships of 3000 tons can reach Iquitos, Peru, 3700 km (2300 mi) from the river's mouth, the farthest point from sea of any port serving ocean traffic.

During new and full moon a tidal bore, or wave front from the ocean, sweeps some 650 km (more than 400 mi) upstream at speeds in excess of 65 km/hr (40 mph). This phenomenon often causes waves up to 5 m (16 ft) in height.