My in-laws came up to Montreal for a week, and we were looking for things to do, and stumbled upon this cruise when strolling through the old port.
They offer 60 and 90 minute rides. I asked about the difference, and the 60 minute cruise goes the same locations as the 90 minute cruise, but the 90 minute cruise is simply a slower pace and is offered around lunch time, suggesting you should take this cruise if you were interested in eating lunch. The 60 minute cruise was $24, and the 90 minute was $28 per person.
The boat ride is very smooth, and the tour guide really does a good job keeping the tourists engaged. Drinks are expensive, we ran up almost a $100 tab in an hour, with only taking 2 alcoholic drinks each for 4 people and an order of chips.
They also offer a day cruise to Quebec City, with overnight stay in Quebec City and cruise back the next day. I plan on giving this one a shot.