The Cousins River is a 4.7-mile-long (7.6 km), primarily tidal river in southern Maine. Rising in the town of Freeport at the junction of Harvey Brook and Merrill Brook, it flows south and forms, for most of its course, the boundary between Freeport and Yarmouth. It ends at the Royal River just west of that river's mouth in Casco Bay.
- U.S. Geological Survey Geographic Names Information System: Cousins River
- Maine Streamflow Data from the USGS
- Maine Watershed Data From Environmental Protection Agency