The Mid-Michigan Rail Bridge just east of the causeway.
This is a good destination for an short hike. Simply park at the Log Booming Circle and follow the tracks towards the river. It’s a lot of fun and a great place to shoot sunrise pix.
If you’re feeling adventurous, as you head back towards Cobb, take a left at the old gazebo. It’s the beginning of a long trail into the river delta. It’s a bit rough but very beautiful.