The Rio da Onça is a water body located within the Rio da Onça State Park in the municipality of Matinhos, within the state of Pará, Brazil. The park itself encompasses an area of 118.5 hectares. Access for paddlers is facilitated through the park's main entrance, which provides basic facilities including a parking area and a reception point. From here, visitors can reach trails that lead to the water. The park features interpretive trails and suspended bridges that cross over flooded areas, which may be relevant for portaging or accessing different sections of the river. Some trails within the park are noted to be tide-dependent and can become impassable during high tide, indicating that the river's water levels and accessibility for paddling are significantly influenced by tidal cycles. This makes tide awareness a critical safety consideration for trip planning. The park infrastructure includes a visitor center and a belvedere, which could offer scenic viewpoints of the surrounding landscape. The overall character of the paddling experience is likely shaped by this protected forest environment, with its network of trails and bridges providing opportunities for exploration beyond the water itself.