The lake, covering about 287 square miles, had been dug out of the surrounding land by a glacier. Lake Simco receives the waters of Lake Couchiching, which thence pass into the Severn River and Georgian Bay. In the dim mists of history, the lake became the starting point of a nine-mile portage, a military supply route. Prior to human encroachment, it had nestled in the forest for eons, untouched by human development. Then aboriginal peoples plied its shores, camping and fishing, while not far away—a mere forty miles—the settlement that would become Toronto was being created.