Combine cranberries, sugar, and water in a saucepan and bring to a boil.
Reduce the heat to medium-high and cook for 5 minutes, until the cranberries are soft.
Let the cranberry mixture cool.
In a large jar, combine cranberry mixture and vodka. Let it sit in a dark place for at least 2 weeks and up to 4 weeks, shaking the jar occasionally. The longer it sits, the more the flavors will develop and mellow out.
Strain out all the cranberries and any sediment through a fine-mesh strainer or cheesecloth. If you want it crystal clear, you can strain it twice. The finished liqueur stores well for a year plus in a well-sealed bottle kept out of direct sunlight.
