The skies in Ontario on general are dark as most of the population of Ontario lives in the southern west tip so a short drive north allows you to get to some really dark skies.
Barrie is the furthest South which is somewhat useful for dark skies. South of this area and you need to use LPR filters for other aids to increase the contrast.
Just north of Barrie are a number of great sites for observing. some of these places have been given their own page with directions and general conditions.