Rattray Marsh Conservation Area is one of my favorite walking trails in the area. It's accessible via the Waterfront Trail in Mississauga (Ontario, Canada), which connects to Jack Darling Park. Rattray Marsh is not a Mississauga park, but under the aegis of the Credit Valley Conservation Authority (CVC). It's a haven for inner city wildlife, and a great favorite of birders and hikers, but not cyclists. The trail is a footpath through the marsh - no bikes allowed.
For more information on Rattray Marsh, see the CVC site.
For photos and googlemap this area and Jack Darling park in winter see this earlier blog post.