Loughborough Lake is a lake in Eastern Ontario, Canada. The lake is mostly in the municipality of South Frontenac, Frontenac County, except for the southern tip which is in and on the northern border of the separated city of Kingston, and is about 20 km north of the town centre of Kingston. Loughborough Lake is in the Great Lakes Basin, is 24 km long and 18.90 km2 in area, with many small islands, and has 119 km of shoreline. Loon Island in the centre of the lake is privately owned by actor Dan Aykroyd.