Free Family Day Tomorrow

We are taking out kids tomorrow to the city beach in Port Clinton, OH on Lake Erie. The city beach is free and there is a nice park with restrooms right across the street from it. We are packing a picnic lunch and plenty of drinks/snacks. We are taking a bucket of sand toys and the camera. When we get tired, we will drive the 2 1/2 hours home. All we will spend is a tank of gas...What can you do for free with only a tank of gas?