| Black River | |
| Pushpin Map: | Canada Southern Ontario |
| Pushpin Map Caption: | Location of the mouth of the Black River in southern Ontario |
| Subdivision Type1: | Country |
| Subdivision Name1: | Canada |
| Subdivision Type2: | Province |
| Subdivision Name2: | Ontario |
| Subdivision Type3: | Region |
| Subdivision Name3: | Central Ontario |
| Source1: | Hosiery Lake |
| Source1 Location: | Algonquin Highlands, Haliburton County |
| Source1 Coordinates: | 45.2592°N -78.7144°W |
| Source1 Elevation: | 424m (1,391feet) |
| Mouth: | Severn River |
| Mouth Location: | Ramara, Simcoe County |
| Mouth Coordinates: | 44.7522°N -79.3114°W |
| Mouth Elevation: | 219m (719feet) |
| River System: | Great Lakes Basin |
| Tributaries Left: | Head River |
The Black River is a river in Simcoe County, the District Municipality of Muskoka, the City of Kawartha Lakes, and Haliburton County in Central Ontario, Canada.[1] It is part of the Great Lakes Basin, and is a right tributary of the Severn River.
The river begins at Hosiery Lake and flows southwest to Raven Lake, then passes under Ontario Highway 35 and into the municipality of Lake of Bays, District Municipality of Muskoka. It continues southwest into Minden Hills, Haliburton County, then back into Muskoka District in the municipality of Bracebridge, passes under Ontario Highway 118 and flows by the community of Vankoughnet, and enters the city of Kawartha Lakes. The river turns west, flows over the Ragged Rapids, exits Kawartha Lakes, briefly forms the border between Simcoe County and Muskoka District, flows through the Big Eddy, then reaches the community of Cooper's Falls in the municipality of Ramara, Simcoe County. It turns south, then heads west, takes in the left tributary Head River, turns north, and reaches its mouth at the Severn River's easternmost outflow from the latter river's source at Lake Couchiching. The Severn River flows to Lake Huron.
It is a common misconception that the Black River flows into Lake Couchiching. This was a problem for lumbermen in the 1860s, who established the Rama Timber Transport Company, to move logs from the Black River to Lake Couchiching.