Founded in 1750, one year after Halifax, Dartmouth is Halifax' counterpart just across the harbor. It is more residential than Halifax, and the downtown area lacks the capital's charm and bustle, but it can make a pleasant base, since getting to Halifax by bus or ferry is so easy.
It's definitely worth a day trip just for the short cruise across the harbor on the ferry, the oldest saltwater ferry system in North America. Alderney Gate houses Dartmouth's ferry terminal.
Dartmouth Heritage Museum displays an eclectic collection in Evergreen House, the former home of folklorist Helen Creighton, who traversed the province in the early 20th century recording stories and songs. Tickets include same-day admission to the 1786 Quaker House, the oldest house in the Halifax area, which was built by Quaker whalers from Nantucket who fled the American Revolution.
Shubie Campground, the only campground accessible from Halifax on public transportation, is privately run and municipally owned. Facilities include showers and a laundry.
Haligonians head to Dartmouth just for the massive buttery chocolate croissants at Two If By Sea. But be warned, they are usually sold out by about 1pm. Even sans pastries, it's a hip place to stop for coffee and people-watching on a sunny day, with a distinctly Dartmouth atmosphere.