Wash the cranberries and place them in a medium or large pot with the water and sugar.
Place pot over medium heat and cook until the berries have popped and there's a thick syrup, about 20-25 minutes.
Run syrup through a fine mesh sieve, pressing all of the pulp out. Discard skins and refrigerate until ready to use.
Frozen Cranberry Daiquiri
In a freezer proof container combine rum, cranberry syrup, lime juice and agave and freeze overnight. (You're likely planning to make more than one cocktail, multiply as needed and make sure to mark your containers so you know how many cocktails are in each).
When ready to serve, combine the cocktail mixture in a blender with 8-10 ice cubes (for each drink) and pulse until smooth.
Pour into a glass rimmed with sugar and garnish with lime and cranberries.
One drink recipe makes one large drink or two small drinks. For reference, 3 recipes filled the five glasses pictured in the post.
This recipe can also make a chilled but not frozen daiquiri. For chilled daiquiris, there's no need to freeze the ingredients beforehand. Just place them in the blender and pulse with the ice cubes until the mixture is smooth.
The cranberry syrup recipe makes about 4 cups, enough for about 20 drinks.
The cranberry syrup will look gritty and as it cools will have a jam like texture. If you'd like it to look smoother, you can puree it in a blender, but there's really no need to do this since it will be blended later. I did try blending it and it came out looking like cranberry curd. Much more appetizing looking if you plan to have a bar set up with cocktail ingredients.