My wife & I just spent several weeks up in Nova Scotia this summer.
In Halifax, plan a few hours at Maritime Museum of the Atlantic, fantastic museum. There is a touristy area on the harbour, next to Maritime Museum, also old fort (Halifax Citadel) that is walkable from downtown. Take the ferry back\forth the harbor for few bucks and pleasant ride. If you take the ferry over to the Alderney ferry port go to Humble Pies (77 King St, Dartmouth, NS B2Y 2R7, Canada) for some great meat pies.
We did some Halifax hiking, I highly recommend the Salt Marsh Trail, especially on a foggy morning, very surreal, flat hiking across the bay on an old railway bed.
If you have access to a car, some great hiking at "Kejimkujik National Park", we camped there for about a week, lots of trail to explore and canoes you can rent.
Enjoy your trip