Mattawa is a town in northeastern Ontario, Canada, at the confluence of the Mattawa and Ottawa Rivers in Nipissing District. Mattawa means "Meeting of the Waters" in Ojibwa. In 1615 Etienne Brulé and Samuel de Champlain were the first Europeans to pass through this area.
The area was first inhabited by native peoples who used the Mattawa River as an important transportation corridor for many centuries. In 1610, Étienne Brûlé and in 1615, Samuel de Champlain were the first Europeans to travel through the Mattawa area. For some 200 years thereafter, it was a link in 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), before continuing on to Lake Nipissing.
Other notable travellers passing by Mattawa included Jean Nicolet in 1620, Jean de Brébeuf in 1626, Gabriel Lallemant in 1648, Pierre-Esprit Radisson and Médard des Groseilliers in 1658, La Verendrye in 1731, Alexander MacKenzie in 1794, and David Thompson in 1812.
In the 1820s and 1830s, the Hudson's Bay Company sent canoe brigades from their Fort Coulonge Post to this river junction in order to trade furs. In 1837, a permanent post was established which was relocated in 1843 to shores of the Ottawa River in the centre of present-day Mattawa. After the fur trade diminished, the post traded general merchandise to supply lumbermen and eventually closed in 1908.