Arroio

Arroio lies within the Jacuí river country of Rio Grande do Sul, southern Brazil. The Jacuí rises in the highlands east of Passo Fundo and runs south and then east for nearly three hundred miles. Its lower course gathers the Taquari, Caí, Sinos and Gravataí rivers before passing Porto Alegre and widening into the Guaíba estuary, then Lagoa dos Patos, a large coastal lagoon connected to the Atlantic.

Boats could ascend the Jacuí as far as Cachoeira do Sul, and the river and lagoon system connected the southern Brazilian interior with the Atlantic coast. Porto Alegre, founded in 1772 on the Guaíba shore, became the port through which the region's goods moved.