So glad I made time to take the ferry to Levis and back. For $7.50 round trip, it's a fun and affordable way to see the city from a different vantage point. I did not get out and explore Levis, but in the summer it looks like there are some nice parks and areas to walk around there.
Reading old reviews, it looks like the ferry used to run every half hour but currently it is every hour. The ferry from Quebec to Levis departs on the 30 and the ferry from Levis to Quebec departs on the 00. I recommend taking the 4:30pm ferry over and catching the 5:00pm back, if you are here in the winter because it coincides with the sunset. The actual ferry ride is about 15 minutes and you can't stay on the boat, you must disembark at Levis. So I just got off, waited in the terminal for 10-15 minutes and then walked back on.
You can reserve a ticket online in advance but it wasn't near full when I went. I just showed up at the terminal a few minutes before and bought my ticket at the desk.
At the terminal and on the ferry, there are vending machines in case you want a drink or a snack.
It is a commuter ferry and when I went I think I was the only tourist (or at least, no one else was taking photos and most people chose to sit inside because it was cold!).
Riding this ferry in the winter is a really unique experience because you can see and hear the ship makes its way across the chunks of ice on the river. There is nothing like it!