TransLink day passes are available in the candy vending machines in the Langdale ferry waiting room at the Horseshoe Bay terminal. I discovered this several years ago after calling TransLink.
But be forewarned: you must really search for them. They are in the very bottom row of the machine, easy to miss. Also, you must be sure to purchase the age-appropriate pass, as they are non-refundable.
Happy hunting.
Lynn Sharp, Sechelt