The Kaministiquia River empties into western Lake Superior at the city of Thunder Bay. Kaministiquia is an Ojibway word meaning "river with three mouths". The two other outlets are known as the McKellar River and the Mission River.

Like the Pigeon River, this river was an important part of the water route into western Canada. A fur trading post was established here in 1683 by Daniel Greysolon, Sieur du Lhut ("Duluth"), but this location was eventually abandoned by the French in 1758. The trading post of Fort William was established here in 1803 by the North West Company at the river's mouth.

Kakabeka Falls located on this river is the largest waterfall in the Lake Superior watershed at a height of 39 metres. Kakabeka means "steep cliffs" in Ojibway. There is an ancient legend about a princess of the Ojibway, Greenmantle, who led a Sioux war party over these falls and, in so doing, saved her village.

Tributaries of this river include the:

  • Dog River
  • Shebandowan River
  • Kashabowie River
  • Whitefish River