Thunder Bay is a large bay on the north shore of Lake Superior. The bay is about 50 km long and 22 km wide. It is bordered to the east by the Sibley Peninsula at the southern tip of which is Thunder Cape, marking the entrance to the bay for ships approaching from the east. The peninsula when viewed from the north shore of the lake has the appearance of a Sleeping Giant.
Rivers emptying into the bay include the:
The harbour at Thunder Bay, Ontario is Canada's westernmost port on the Great Lakes.
The Ojibwa called it "Animikie", meaning thunder. French explorers called it "Baie du Tonnerre" which was translated to Thunder Bay in English.