Go to Cornwall Ontario just west of Quebec border. Not sure if charters do these sites from your side of the border. When the St. Lawrence seaway was deepened they sunk ~11 towns I believe. The Fire dept in the area and rescue services used the towns to train in worst case scenarios so not alot of structures left. There are streets which today still just disappear into the river.We did not do the swim down main street but what I remember there are roads, basements, sidewalks still there, the old locks(lock 21) is a shore dive that is totally intact. There is also a intact hydro station (boat dive)- generators and turbines, intake/output all in place 70' the deepest I believe. Small brick building on top was demoed for boat trafic safety. You can enter the water outputs and move into the pipes that exited the generators up to the turbine blades very cool!!! usually a few half decent sized catfish in there. The turbine blades make a funny noise as your bubbles hit and go through them. We only had 1 day of boat diving there and did the lockes on the sun morn shore dive and then had to leave but I'm sure there are other great dives there.