Montreal is (kind of) known for its music and during the summer they have Picnique Electronique. Basically, it was a dance party on the beautiful Jean Drapeau Island. You could bring your own food and drinks and sit in the grass to take a break from the EDM. So much fun, would definitely go again if I had the chance.
PS: On the same island you can bike the Formula 1 race tracks which I didn't get to do, but is on the list for next time!