The second largest Province in Canada will surely have some amazing floats.
The Elora Gorge route has been described as 95% calm, 5% rapids, but the rapids sections are very intense and shouldn't be taken lightly. You'll see a lot of helmets on the river, and for good reason. Be safe, not dumb. The float takes about 45 minutes and it is believed that you can only take the rental innertubes out on the river. Check with the office and bring a Dreamboat just in case. This route is operated by local Convervation Authority. They rent tubes and apparently operate a shuttle service. The river is closed for tubing at times, so check the conditions page here:: https://www.grandriver.ca/en/outdoor-recreation/Beach-and-tubing-conditions.aspx Also of note, alcohol is banned in the park.
Grand River - Brantford Route
This route of the Grand River takes about 4-5 hours to complete. There is a dam around the corner from the Blake Ave exit, so pick your exit point wisely.
Grand River - KITCHENER Route
This route on the Grand River takes about 3-4 hours to get down. The river is reportedly only 5 feet deep or less in the Summer months and glides along pretty slowly. No rapids to speak of, so this one is safe for the family.