Arroyo Pos Pos is a stream located in the Entre Ríos Province of Argentina, near the city of Concepción del Uruguay. Entre Ríos, whose name translates to "between rivers," is a province defined by its rich network of waterways, and Arroyo Pos Pos is one of the many arroyos — small to medium-sized streams — that drain the rolling grasslands and gallery forests of this region. The surrounding landscape is characteristic of the Mesopotamia region of northeastern Argentina, where subtropical conditions, fertile lowlands, and an extensive hydrological network create productive freshwater fishing environments.