salter water fishing closest to Toronto?

Being from Toronto, we don't have any salt-water fishing location. So I am
wondering for those that are from here, where is the closest salt-water
fishing location that can be reached by car (reasonable distance).
I thought perhaps James Bay or Hudson's bay might be the closest? Anyone
ever gone there? how is it like as a fishing place. Are the catches
plentiful?

Is the St. Lawrence River just off Montreal area considered salt water? or
is it still too fresh from the fresh water pouring into it from Lake
Ontario? If so how far down river do you have to go to get Salt water on
the St. Lawrence.