Río de la Plata - History | Britannica
Río de la Plata - Río de la Plata - History: The Río de la Plata was first explored by Europeans in 1516, when an expedition led by Juan Díaz de Solís, chief navigator of Spain, traversed the estuary as part of its effort to find a route to the Pacific; the estuary was temporarily named in memory of Díaz de Solís after his death on its shores at the hands of unfriendly Charrua Indians.