The Río Colastiné is a branch of the Río Paraná approximately 50 kilometers long, located in the province of Santa Fe within the Departamento La Capital, running between the cities of Santa Fe and Paraná. Its name derives from an indigenous tribe of the region. The river's inlet draws from the right bank of the main Paraná channel near the locality of El Cerrito on the Entre Ríos coast, while its outlet lies downstream of the city of Paraná, near the santafesina city of Coronda — though Coronda itself sits on the Río Coronda, a separate Paraná branch.

Being a secondary arm of a lowland river system, the Colastiné is characterized by a continuous tendency to shift its channel, which is managed through periodic dredging. This dynamic, meandering nature is typical of Paraná delta tributaries and is worth keeping in mind when navigating. Between the Colastiné and the main Paraná channel lies a low-lying island known as Isla de Santa Cándida, which is entirely floodable and has no permanent population.

The city of Santa Fe draws its potable water supply from this river, which speaks to its role as a significant freshwater resource in the region. The villa of San José del Rincón, historically the second most important city in the province and now effectively part of the greater Santa Fe urban area, sits on the river's banks.

Paddlers have used the Puente Colgante area of Santa Fe as a departure point, traveling through the Puerto Amarras zone and out toward Alto Verde and the access canal. The river passes sandbars and is frequented by wading birds including herons. The Islote Curupí, a protected natural area with walkways along the riverbank, lies within the broader paddling corridor. The route along Arroyo Miní, which borders Ruta 168, connects back to the Colastiné for a return to Santa Fe. Two major road crossings span the river: Ruta Provincial 1 and Ruta Nacional 168, the latter providing access to the Túnel Subfluvial Paraná-Santa Fe.

Fishing activity on the river targets species including spotted sorubim and trahira, with nearby waters such as Laguna Setúbal and Laguna La Cuarentena also within the general paddling area.