We did this in Seattle - They call them Duck boats, and gave us all duckbill-shaped whistles that make a duck sound. We drove through downtown Seattle with the tourguide giving historical and current information on the sights, and then we hit the water and took a floating tour of Lake Union and its surrounding sights. The tourguide was very funny, and quacked-at passersby and businesses along the route waved and quacked back, it was hilarious!