In reply to French Erick:
I can't comment much on Ottawa, though I know that there is some rock near by, primarily around Kingston, Ont., I believe.
Montreal has a number of crags within fairly easy access and an active climbing community, with even a few outcrops within the city limits. Most of the climbing is north of the city in the Laurentians. Val David, about an hour's drive north of the city is the most popular area with several crags and bouldering areas in close proximity to each other on good granite. Most routes are single pitch, but there are some 2. possibly 3, pitch options particularly on Mt. King. The area has a long (by east coast of North America standards) climbing history stretching back to the 1930s, so most routes are traditionally protected (or top-roped) though some of the newer sectors are well-bolted. Further into the mountains are a good number of other crags, with Mont Nixon, near Mt. Tremblant, being the most well-known with routes of at least 2 pitches.
Several other areas are south, west, or east of the city and some quite close to town, these include Weir and Mt. D'Argent. Further to the south, close to the US border but still not too far from the city are areas such as Mt. Orford (mostly bouldering and sport on volcanic rock) and Mont Pinnacle (Lac Lyster) with single and multi-pitch climbs. Across the border, but still not a far drive are the many excellent crags of the Adirondack Mountains in NY., frequently visited by climbers from the Montreal area.
In winter, ice climbing options are numerous, some very close to town including the famous Montmorency Falls. There are also several climbing gyms in the city for those days when it is even too cold for ice climbing.