My town used to have a duct tape kayak race every year. It was the kickoff to the annual town festival. I did it with my kids. You would be given cardboard, duct tape and a box knife. You had certain amount of time to make a kayak and paddles (though using your hands was generally better than a flimsy paddle). Then there would be races for the kids. They would go half way out in the river and back. Tons of fun. The kids wore life vests and the fire department was out in motor boats. Also, the river is pretty shallow for quite a ways.
