Severn River, 982 km long, rises in the wooded Shield country of northwestern Ontario and flows northeast through Severn Lake to Hudson Bay. Part of the territory inhabited by the Woodland Cree, it was discovered for Europeans in 1631 by Thomas James while searching the bay for a northwest passage. Later in the 17th century the Hudson's Bay Company erected a trading post at its mouth. The river was used by fur traders travelling between the bay and Lake Winnipeg. It was named after the Severn River in the British Isles. Severn Lake and part of the river below the lake are protected as a provincial park.