The name Río de la Plata is also used to refer to the populations along the estuary, especially the main port cities of Buenos Aires and Montevideo, where Rioplatense Spanish is spoken and tango culture developed.

[3] The Río de la Plata begins at the confluence of the Uruguay and Paraná rivers at Punta Gorda and flows eastward into the South Atlantic Ocean.

[2] Though it is generally spoken of as a river, the Río de la Plata is considered by some geographers to be a large bay or marginal sea of the Atlantic Ocean.

Because of deposition of sediments from the heavy stream load carried down from the river's tributaries, the islands in the Río de la Plata generally grow over time.

Currents in the Río de la Plata are dominated by tides reaching to its sources and beyond, into the Uruguay and Paraná rivers.

It includes areas of southeastern Bolivia, southern and central Brazil, the entire country of Paraguay, most of Uruguay, and northern Argentina.

[16][17] The Spanish first explored it in 1516, when the navigator Juan Díaz de Solís traversed it during his search for a passage between the Atlantic and the Pacific Oceans, calling it the Mar Dulce, or "freshwater sea".

Cabot acquired silver trinkets trading with the Guaraní near today's Asunción, and these objects (together with legends of a "Sierra de la Plata" in the South American interior brought back by earlier explorers) inspired him to rename the river "Río de la Plata" ("River of Silver").

The primary export was silver from the mines of Potosí, and imports generally included European luxury goods, slaves, and sugar.

Crown officials and military outposts in Buenos Aires often relied upon profits from illicit trade to support their administrative structures.

Then, Spanish war with Britain and the simultaneous eruption of revolts in the mining regions of Peru led to a shortage of silver, putting strain on the merchant class of Buenos Aires.

During the Cisplatine War, the Río de la Plata was blockaded by the Imperial Brazilian Navy, aiming to cripple Argentine finances and resupply their positions in Colonia del Sacramento and Montevideo.

Squadrons of the newly independent United Provinces of the River Plate, led by the Irish-Argentine admiral William Brown attempted to break the blockade despite numerical inferiority.

[22] In the first major naval engagement of the war, an Argentine squadron left port in the early hours of February 9 to challenge the blockade.

[24] In 8–9 February, an Argentine fleet led by Brown engaged the Third Division of the Imperial Navy on the Uruguay River, inflicting heavy casualties against a disorganized Brazilian squadron.

[25] Near the coast of Ensenada in April 7, four Argentine vessels led by Brown slipped out of port in an unsuccessful attempt to surprise a large Brazilian fleet under the command of Norton.

Two brigs were sunk, and a schooner was heavily damaged, resulting in a decisive Brazilian victory that ensured the Imperial blockade of the Río de la Plata until the Preliminary Peace Convention of 1828.