The Iroquois River — a slow, muddy, tree-shaded stream that eventually flows west into the Kankakee — curves through the northern edge of Rensselaer. A short riverwalk follows it past Weston Cemetery and a couple of small parks, and is a pleasant 30-minute loop on a warm afternoon.
The river was historically important to the area's Native and early settler communities, and the town owes its name to one of those settlers, James Van Rensselaer, who plotted the original village along the riverbank in 1837. Fishing for catfish and bass is still popular off the small public dock at Brookside Park.