Add all of the ingredients for the cranberry syrup to a saucepan and bring to a full boil.Reduce the heat to a gentle boil, simmer, and cook until cranberries have softened, about 10 minutes. Remove from heat and allow mixture to cool.

Once cool enough to handle, strain the cranberry mixture through a fine mesh strainer, pressing the pulp into the strainer to maximize the amount of syrup you get out. Discard the pulp and refrigerate the syrup until ready to use.

Fill glasses with ice and fill most of the way up with ginger beer. Carefully pour in the cranberry syrup, followed by the dark rum. Serve with fresh cranberries and enjoy.

Note: Since dark and stormies are served with a rum floater, the first few drinks are super strong. To lessen the POW, stir the cocktail prior to sipping.