Thunder Bay is a large bay on the northern shore of Lake Superior, in Thunder Bay District, Ontario, Canada. The bay is about 50 kilometres (31 mi) long and 22 kilometres (14 mi) 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 mesas and sills on the peninsula are known as the Sleeping Giant due to their appearance when viewed from Thunder Bay. Notable islands and island chains in the bay include: Rivers emptying into the bay include the: * v * t * e