Muskoka Lakes, chain of lakes, Muskoka District, southeastern Ontario, Canada, about 80 miles (130 km) north of Toronto. They consist of the chain of lakes drained by the Muskoka River into Georgian Bay, the largest of which are Muskoka (15 miles long by 5 miles wide [24 by 8 km]), Rosseau (12 miles by 5 miles [19 by 8 km]), Joseph (12 miles by 4 miles [19 by 6 km]), and Lake of the Bays (13 miles by 6 miles [21 by 10 km]). Once an important lumbering region, the lakes have since become one of the province’s major vacationing areas.