The Keweenaw Waterway is a partly natural, partly manmade waterway which cuts across the Keweenaw Peninsula of Michigan. Parts of the waterway are variously known as the Keweenaw Waterway, Portage Canal, Portage River and Portage Lake. The waterway connects Lake Superior to itself, with Portage Lake (also known as Torch Lake) in the middle.

Originally a small river used by natives for transportation and fishing, the waterway was dredged and extended in the 1860s in a joint venture between the United States Government and several mining corporations. The expanded canal allowed freighters to haul copper from the rich copper mines of the Keweenaw Peninsula out through Lake Superior to larger cities. It also enabled supply boats and freighters to reach the cities of Houghton and Hancock, which supplied goods to most of Michigan's copper region.

The area north of the waterway is locally known as Copper Island, because the waterway separates the northern part of the Keweenaw Peninsula from the mainland.

The only land route across the waterway is to travel on US-41/M-26 across the Portage Lake Lift Bridge.