Stir the cranberry juice, orange juice, and pineapple juice together in a large pitcher or punch bowl until fully combined.
Chill the juice mixture for at least 1 hour, or until it feels cold to the touch all the way through; this keeps the ginger ale from going flat the moment it hits the bowl.
Just before serving, pour in the chilled ginger ale slowly and give the punch one gentle stir, just enough to combine without knocking the fizz out of it.
Float the frozen cranberries and orange wheels on top of the punch.
Ladle the punch into cups or rocks glasses filled with ice.
Garnish each glass with a rosemary sprig and a few extra cranberries.
Good to Know
Make the juice base up to a day ahead and keep it refrigerated; add the ginger ale and garnish only at serving time so the fizz survives.