There is a vibrant community of river surfers in Montreal, Quebec...but they might not want you to know that. They worry about their secret surfing spots being shut down by the municipal government or the waves becoming crowded, the wait times too long, about the the 'vibe' being lost. The currents of the St. Lawrence, which are particularly strong near the island of Montreal, pair with the myriad large boulders (or depressions in the river floor?) beneath the surface of the water to create a constant wave that surfers have learned to take advantage of. The sport of river surfing differs dramatically from ocean surfing and consequently, does not get the same level of respect as big-wave-riding-Xgames-type surfing. But river surfers are proud of their skills, their community, and their own inland surfing spot.
Find more info on the Montreal river surfing scene here.
Montreal river surfing was written about in the New York Times here. The article includes interesting reporting, including info about the first person to identify and attempt to surf the endless wave behind Habitat 67.