Leo Y.
Google
Yes, the price is not cheap, but the 2 hours 15 minutes boat ride was worth every penny. You get to visit the US soil without needing a passport, very interesting.
If you in Waterton Park, this is the main attraction that you should try to get to. The boat is almost 100 years old, and it is very nice boat. The staff is awesome, especially captain Kevin (aka captain Steve). Super funny and very informative. One note worthy incident, was that somebody dropped a water bottle into the water when the boat was docked, and Nate when down into the water to fetch the water bottle for the gentleman. It's a very Canadian courtesy from the staff.
Please don't forget to tip the staff. 95% of the people did not, but I think they deserve a tip for the services.