This summer in Montreal, I am repeatedly baffled by the options of outdoor activities available really close to Montreal if one only googles around a little. Case in point: Les Iles-de-Boucherville. This National Park is a mere 20k from downtown Montreal, and thus made the perfect outing location for an extensive bike ride. You (and your bike) can get onto the islands with one of three tiny ferries for $6 per return ticket (including the park entrance fee), and the park has another 21 km of bike paths perfect for exploring. The best part - you can even rent kayaks and canoes there!
Though, be forewarned - the "trip through the wilderness" that the Montreal Gazette advertized only starts after you survive what pretty much amounts to a cross between Jersey Shore and the Cote d'Azur of Montreal - tons of pretentious speedboats with equally obnoxious passengers blasting dance music, chugging beer and "enjoying nature". Huh.
Finally, it's advisable to take note that ferries depart the mainland at every full hour and leave from the islands at every half hour, and that the last one leaves at 5.30 on the dot - my friend and I arrived at the dock at 5.26 and were very happy not to have to swim ashore (since the only road leading up to the islands is the highway.) Happy exploring!