Paper charts, or electronic? On the electronic front I've used
C-map and
Navionics. Both are good.
One question, though. The St Lawrence headwater is
lake Ontario, not Huron. If you are going to Huron, you will also want charts of the Trent Severn Waterway which connects
Ontario with Huron. Alternately, you can go to the western end of
Ontario, through the Welland
Canal to Erie, then at the western end of Erie you can get up into Huron. I'm not sure of the name of the connecting waterway between Erie and Huron.