I visited Halifax this past October. My main goal was to eat as much lobster and oysters in a week which went pretty well thanks to events like the Halifax Oyster Festival. Here are additional things you could do in between meals ;)
1 - Go for a boat ride
Halifax offers plenty of boat tours for whale watching, nightlife or learning about the history of the area. A really cheap and satisfying option is the ferry that leaves for Dartmouth. I believe it costs less than $3 and it takes 12 minutes or 24 minutes roundtrip. The ferry leaves you at Alderney Landing Community Center which hosts a few stores and restaurants including the awesome Casaroma Wellness Centre featuring natural body and hair care products.
2 - Get a local beer by the water
Stillwell has a cool bar in a container just by the water during the summer and early fall. It's the perfect stop after getting a bite at the Halifax Seaport Farmer's Market.
3 - Get moving at Seven Bays Bouldering
Seven Bays Bouldering in North End is a gorgeous and modern location to get introduced to bouldering! If that sounds too hardcore for you, you can also just have a beer and get some work done in the open area.
4 - Get your drink on at Field Guide
Also, part of North End, Field Guide has one exciting cocktail list! They also offer a modern menu made to be shared.
5 - Lion & Bright
Lion & Bright is a café by day and a bistro by night. I found it a great place to get some remote work done while eating for cheap. I also really enjoyed the Local Source Market that's next door but accessible through the café. They feature tons of local products which makes it the number one stop to find gifts from Halifax.
6 - End your evening at a speakeasy-inspired bar
Noble should be on your to-do list no matter what. I loved the experience that involved getting to the bar, the drinks that almost always featured Bourbon and the great music playing all night. To get in, you need to say the password (that changes every week) at The Middle Spoon Desserterie & Bar.
Hope you enjoy Halifax! Don't forget to buy fresh lobster at the airport on your way home ;)