The Mattawa River, a Canadian Heritage river, served as a major waterway for native peoples, explorers, and the voyageurs. In search of beaver pelts to trade in Montreal, the voyageurs travelled the 2,000-km journey from Montreal to Fort William on Lake Superior. The Mattawa River was one of the most arduous sections of the trip, with its many portages, white-water rapids and perils of the wilderness.

The Mattawa River is today protected as a waterway park along most of its 64-kilometre length. Samuel de Champlain Provincial Park is a 2,550-hectare natural environment park along an eastern section of the river.

The Mattawa winds along a 600-million-year-old faultline in the earth's crust. Although much of the orginal forest was felled before 1880, towering groves of hemlock and yellow birch still still stand in the park's northern reaches. A hybrid of wild rye and bottle brush grass is found nowhere else but in the park. Smooth roses grow by park roads in late June, and an array of cardinal flowers grow along the Horserace Rapids in August.

Wildlife includes moose, wolves, bear, and white-tailed deer, along with more than 200 species of bird including loons, common mergansers, black ducks and wood ducks.