Lagoa dos Patos is the largest coastal lagoon in South America and the largest lagoon in Brazil, a truly extraordinary fishery stretching approximately 290 kilometers (180 miles) from north to south and reaching widths of up to 71 kilometers (44 miles) across the state of Rio Grande do Sul in southern Brazil. Covering roughly 10,100 square kilometers, this massive shallow estuarine system sits at the heart of one of the most biologically productive coastal environments on the continent. The lagoon is separated from the Atlantic Ocean by a sandbar known as the São José do Norte Peninsula, approximately 8 kilometers wide, which shelters the lagoon from direct oceanic influence while allowing brackish water exchange near its southern outlet at the city of Rio Grande. Fed primarily by the Jacuí-Guaíba river system to the north and the Camaquã River from the west, the lagoon drains southward through the Rio Grande Channel into the Atlantic. The northern reaches near Porto Alegre are predominantly freshwater, while the southern estuary transitions to brackish conditions, creating a remarkable diversity of fishing environments within a single water body. With an average depth of approximately 5 to 6 meters and a catchment area exceeding 200,000 square kilometers, Lagoa dos Patos is a shallow, wind-influenced system where conditions can change rapidly and dramatically.