The Kaministiquia River is a Canadian river which empties into western Lake Superior at the city of Thunder Bay. Kaministiquia is an Ojibwe word meaning "river with islands" due to two large islands (McKellar and Mission) at the mouth of the river. The delta has three branches or outlets: the southernmost is known as the Mission River, the central branch as the McKellar River, and the northernmost branch as the Kaministiquia. Residents of the region commonly refer to the river as the "Kam". The three branches of the river at the delta were extensively dredged and widened by the federal Department of Public Works in the early twentieth century to facilitate navigation.

Like the Pigeon River, this river was an important part of the water route into western Canada. During the French regime, two fur trading posts were established at the delta (1679 and 1717). The trading post of Fort William was established here in 1803 by the North West Company at the river's mouth. After 1883, the lower Kaministiquia river was heavily industrialized by the Canadian Pacific Railway with railway yards, coal yards and docks, grain elevators, shipping docks, and sawmills. A double-deck bascule bridge (the Jack-knife bridge) was built by the CPR in 1913 to allow trains and vehicles to cross from the mainland to Mission Island.

Kakabeka Falls located on this river is the largest waterfall in the Lake Superior watershed at a height of 39 metres. Below these falls, the river flows through an extensive floodplain created by an ancient predecessor that flowed through this region following the last ice age.

The river has been depicted by many prominent Canadian artists such as William Armstrong (1822-1914), Frances Anne Hopkins (The Red River Expedition at Kakabeka Falls, 1877) and Lucius Richard O'Brien (Kakabeka Falls, 1882).

Tributaries of this river include the:

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

See also

• List of Ontario rivers