Highest tides in the world! Supposed to be pretty cool. My parents were just there, and they recommend Digby, for their world famous sea scallops, so that's worth a stop if you're in the area...
Are you driving through Canada (Montreal etc?) or the States? You're in Minnesota, aren't you? There's some GREAT fishing just north of you if you're planning on coming this way....
If you're a history buff, Port Royal is considered to be one of the earliest settlements in North America...
It's a bit out of your way, but Lanse-aux-meadows on the island of Newfoundland is the first European settlement in North American (Leif the Lucky)
St. John NB has the famous reversing falls, in which the water flows downhill, then uphill, based on the tidal flow...
There's plenty of opportunity to whale watch, and the grand banks are full of fish (or used to be, before the fishing trollers of Japan sucked up most of the commercial fish)
There's a big botanical garden at Annapolis, NS
Probably a thousand other things too, but this is what leaps to mind...