Saint John, New Brunswick
The people of Saint John are the nicest I have met anywhere in the world. There is really something special about them.
The huge difference in the tide at the Bay of Fundy is the main reason to visit Saint John. Reversing Falls changes direction at high and low tide. It is hard to see it flow in both directions with the time you have in port, though. There is a jet boat "thrill ride" through the falls which is quite the adventure. It apparently gets especially rough at low tide when no one under the age of 13 is allowed. It is best to reserve in advance.
We hired a taxi for 3 hours ($50 per hour) to take us to Saint Martin about an hour away in order to explore the sea caves at low tide. This was awesome! You have to time it right, though, or you will not be able to explore them. You can check the tide schedule on line to see if it is worth the trip.