The Missinaibi River is a river in northern Ontario, Canada, which flows northeast from Missinaibi Lake, north of Chapleau, and empties into the Moose River, which drains into James Bay. This river (including Missinaibi Lake and Moose River to James Bay) is 755 kilometres (469 mi) in length. It is one of the longest free-flowing and undeveloped rivers in Ontario.
The river's name means "pictured waters" in the Cree language which is thought to refer to the pictographs found on rock faces along the river.
The three main posts, all at times called Brunswick House or similar were
Wapiscogamy House: In 1776 Thomas Atkinson from Fort Albany, Ontario went 200 miles upriver and established Wapiscogamy House on the west bank of the river. It was rebuilt in 1781, named Brunswick House, closed in 1791, and re-opened from 1800-1806.
Missinaibi Lake House: In 1777 John Thomas was sent from Moose Factory to build a post at Michipicoten on Lake Superior. He selected a better location at the outflow of Missinaibi Lake and called it Missinaibi Lake House. It was occupied each summer until it burnt in 1780. The site was re-occupied from 1817 until about 1821. It was reopened in the early 1870s and in 1879 renamed New Brunswick House. When the railroad was built just north of the lake in 1912-13 operations were moved to the new town of Peterbell and the post was closed in 1914. Around 1980 there were left a few cellar holes and collapsed buildings.
Macabanish House: In 1788 William Boland established a post between the other two on Micabanish Lake on a tributary west of the river. Its success led to the closing of Wapiscogamy House. In 1799 it was named New Brunswick House and the lake renamed Brunswick Lake. It was the chief post until 1879 when it, and its name, were transferred to Missinaibi Lake. Around 1990 the clearing where it stood was visible from the air. Brunswick House First Nation gets its name from this and the one on Missinaibi Lake.
Today, the river is used for canoeing, fishing and camping. Recreational use is facilitated by an arrangement which allows canoeists to load their boats on a train so they can be returned south, after canoeing the wild stretches of the river. The river is managed as a provincial waterway park and was designated as a Canadian Heritage River in 2004.
The entire length of the Missinaibi River from Missinaibi Lake to the Moose River is protected and part of the Missinaibi Provincial Park. The park also includes Missinaibi Lake, Brunswick River, Brunswick Lake, Little Missinaibi River, and Little Missinaibi Lake.