[1] From Lake Talon to Mattawa the river flows through a rock-walled canyon up to 150 metres (490 ft) in places.

Tributaries include the: The Porte de l'enfer (Hell's Gate) is a peculiar cave in the river's bank speculated to be a native ochre mine.

[4] For some 200 years thereafter, it formed part of the important water route leading from Montreal west to Lake Superior.

Canoes travelling west up the Ottawa turned left at "the Forks" (the mouth of the Mattawa) to enter the "Petite Rivière" ("Small River", as compared to the Ottawa), reaching Lake Nipissing by way of "La Vase Portage", an 11-kilometre (6.8 mi) stretch of water and portages.

[4] In the 19th century, the river provided access to large untouched stands of white pine.

An additional 108.8 square kilometres (42.0 sq mi) of Crown Land was added along both shores, and extending it on the eastern side of Samuel de Champlain Park towards the town of Mattawa.

Permitted activities are mountain biking, boating, canoeing, fishing, hiking, hunting, snowmobiling, and swimming.

The Mattawa River is a popular destination for weekend canoe camping trips, that can be travelled in both directions.

There are two short whitewater sections inside Champlain Park but which become shallow and a rock garden in low water.

The race runs from Olmsted Beach on Trout Lake in North Bay to Mattawa Island Conservation Area, through open water, rapids, and portages.

There is also a 13-kilometre (8.1 mi) race which runs from Samuel de Champlain Provincial Park to the finish link at the Mattawa Island Conservation Area.