Cobourg is a town situated in the province of Ontario, Canada. It serves as the largest town and the seat of Northumberland County. The community is located in Southern Ontario, approximately 95 km (59 mi) east of Toronto and 62 km (39 mi) east of Oshawa.
The town is positioned along Highway 401 and the former Highway 2, bordering Lake Ontario to the south. It is surrounded by Hamilton Township to the north, east, and west, with its nearest neighboring community being Port Hope, located 7 km (4 mi) to the west.