The Rio Guaxindiba is a river located in the State of Rio de Janeiro, Brazil, specifically flowing through the municipality of São Francisco de Itabapoana. Its final stretch passes through a flat region of mangroves within the Guanabara Ecological Station, a protected area spanning 1,936 hectares, before discharging into the Atlantic Ocean at Guaxindiba Beach. This estuary environment, where the river meets the sea, defines the primary paddling character. The river flows through a mangrove ecosystem, suggesting a relatively calm, flatwater experience suitable for kayaks and paddleboards, with the potential for winding channels through the mangroves. The area is noted for its natural scenery, centered on the mangrove habitat which is ecologically significant. A key access point for paddlers is at the river's mouth, Praia Guaxindiba (Guaxindiba Beach), which serves as a hub for boat tours and water sports. This beach area in São Francisco de Itabapoana is a recognized put-in/take-out location, though specific details on formal boat ramps are not provided. The presence of the Guanabara Ecological Station indicates that paddlers should be aware of and respect any environmental protection regulations that may apply to water-based activities within this conservation unit. The overall vibe is one of a natural, protected coastal wetland area. The river's proximity to Guaxindiba Beach suggests that ocean conditions at the mouth, including tides and wave action, could influence the paddling experience, particularly near the foz, or river mouth.