Go to
Welcome To Torpedo Rays Scuba they have a list along with directions and maps of quite a few dive sites in and around the Halifax area. The arrow in Cape Breton is a good dive..there is a wreck in Country Harbour that the name of is escaping me at this time. like mentioned HMCS Sag is great..did a lot of my dive training there. Also with the coastline that NS has just pick a shore and dive it. Thats what I do. (get permission with land owners and have a flag)
