I've been going to Belle River for years. It's only about a 25 minute drive from downtown Detroit and has a fantastic beach and waterfront to Lake St. Clair -- you can walk out into the water hundreds of feet before the water would get over your head. It's seldom crowded and there's a great pier and park there as well as wonderful quiet roads to bike on. It's definitely a favorite place of mine to spend the day. To get there, just cross over into Canada from the U.S. over the Ambassador Bridge, continue on Huron Church just a few miles, get on E.C. Row Expressway and go West for about 20 minutes and the Belle River pier, beach, and marina will be on your left. Enjoy!
Video of Belle River, Ontario, Canada