Eramosa River

The Eramosa River is a river in Wellington County in southwestern Ontario which rises near Erin, Ontario, and flows southwest through the city of Guelph, where it joins the Speed River, which then enters the Grand River in Cambridge.The river flows through an area covered with several hundred glacial potholes near Rockwood, one of the largest being the Devil's Well, deep, wide at the top and at its base.