The "magic" cooler at the cove on the side closest to the Goofy pool is free for the snacking. On my last cruise, the glass was fogged over for most of the day and you could not see what was inside, but so worth sliding those doors open.
All the beverages have a fee, but many times the hostess/host will included a snack from the cooler when they bring your beverage, if you haven't already headed over and made your choice.
Pj