St. Marys River (Maryland)

The St. Marys River (sometimes spelled St. Mary's River) is a 22.3 mi river in southern Maryland in the United States. It rises in southern St. Mary's County, and flows to the southeast through Great Mills, widening into a tidal estuary near St. Mary's City, approximately 2 mi wide at its mouth on the north bank of the Potomac River, near the Chesapeake Bay to the east.