I just returned from my Canada/New England cruise yesterday. Absolutely loved Halifax and highly recommend Mel from Down East Tours. It was the best excursion we've ever done and since it was private, we were able to customize it to what we wanted to see. I actually found Mel to be slightly cheaper than the cruise line. Plus, all your money is going to the local economy and not the cruise line.
https://www.downeasttours.ca/