Not sure. I have been downtown @ Chicago Harbor and worked it only a few times. I am at the other lock Chicago... On Calumet we do 10s 1,000 of pleasure craft... But it's not as crazy as the crazy days downtown. It is a bit congested on Chicago River and lock there is 60% smaller... I can imagine the tour boat guide was right! Get one boat deviating from norm, kinda jazzes up the flow of traffic.