Rudeney thank you for the correct information,
CBSA has an special arrangement with visiting cruise ships from US ports. We still have to test 48hrs before boarding ( Royal Caribbean requirement also) the ship and 72hrs before arriving at an Canadian port of entry complete the ArriveCAN app or web site.
If you were driving across the border you would just need to be vaccinated and say you were symptom free on the app or web site which is linked to your passport.
CBSA will do random testing.