An American friend recommended me to do this if I ever visited Boston. I thought it was silly but now I tell you it’s a must-do! The best option is to do it on your last day so you can say goodbye and see everything in case you missed something.
Tour is 20$ and is a complete tour thought the city with a guide that makes the ride funny and informative. And the duck gets on the water! You get both bay and city guides at once!