Mouth of the Amazon River, Brazil1.6N 49.9W
The Amazon River of South America is the largest river in the world by volume and has the world’s largest drainage basin. Here, it can be seen flowing through the Brazilian rainforest to its mouth, carrying an immense load of sediments into the ocean.
The Amazon estuary is some 330 kilometres (210 mi) wide. The width of the mouth of the river is usually measured from Cabo do Norte to Punto Patijoca. This means that the Amazon is wider at its mouth than the entire length of the Thames in England.
Following the coast, a little to the north of Cabo do Norte, and for 160 kilometres (99 mi) along its Guiana margin up the Amazon, is a belt of half-submerged islands and shallow sandbanks.
Here the tidal phenomenon called the bore, or pororoca, occurs, where the depths are not over 7 metres (23 ft). The tidal bore starts with a roar, constantly increasing, and advances at the rate of from 15–25 km/h (9–16 mph), with a breaking wall of water from 1.5–4.0-metres (5–13 ft) high.
The bore is the reason the Amazon does not have a protruding delta; the ocean rapidly carries away the vast volume of silt carried by the Amazon, making it impossible for a delta to grow past the shoreline.