Rio de la Plata, South America – October 10th, 2008
The Río de la Plata (meaning the Silver River in English), whose mouth can be seen in the center of the image as a funnel-shaped indentation, is the estuary formed by the merging of the Uruguay River and the Paraná River. It is located on the southeastern coastline of South America, extending 290 kilometres (180 mi) from where the rivers meet the Atlantic Ocean.
The estuary is the widest in the world: where the rivers converge, it is 48 kilometres (30 mi) wide, and it runs to the southeast growing to 220 kilometres (137 mi) wide where it opens on the Atlantic Ocean.
The river forms part of the border between Argentina and Uruguay; in this image we can observe those two countries as well as Brazil. Argentina’s capital city and major port, Buenos Aires, is located is the southeast part of the estuary, while Uruguay’s capital and major port, Montevideo, is in the northeast part.
The basin drained by the main tributaries of the Río de la Plata (the Uruguay and Paraná, and the important Paraná tributary, the Paraguay) covers approximately one fifth of South America, including area in southeastern Bolivia, southern and central Brazil, the entire nation of Paraguay, most of Uruguay and northern Argentina. An estimated 57 million cubic metres (2 billion cubic feet) of silt is carried into the estuary each year, where the muddy waters are stirred up by winds and the tides. In the image that silt is visible as the brown in the water of the rivermouth.
North of the Rio de la Plata and Uruguay, along the Brazilian coast, we can see two other brown colored bodies of water: Lagoa dos Patos (Lagoon of the Ducks) and Lagoa Mirim. The former is the second largest lagoon in Latin America, located in the state of Rio Grande do Sul. It is 174 miles (280 km) long, has a maximum width of 44 miles (70 km), and a total area of 3,803 sq. mi. (9,850 km). A 5 mile (8 kilometer) wide sandbar separates it from the Atlantic Ocean. The lagoon is evidently the remains of an ancient depression in the coastline shut in by sand beaches built up by the combined action of wind and current. It is at sea level, but its waters are affected by the tides. Lagoa Mirim is located just south of Lagoa dos Patos; the two are connected by the navigable São Gonçalo Channel. The light sands of the beaches near the lagoons are clearly visible in the image.