Combine sugar, corn syrup, and water in a 3-quart saucepan over medium heat; cook and stir until sugar dissolves and mixture begins to boil, 5 to 10 minutes. Stir in butter; cook, stirring frequently, until mixture is thick and syrupy and a candy thermometer inserted into the center of the syrup, not touching the bottom, reads 230 degrees F (110 degrees C), 10 to 15 minutes.
Mix almonds and cranberries into the sugar mixture; cook and stir until temperature reaches soft-crack stage at 280 degrees F (138 degrees C), 10 to 15 minutes. Stir constantly until mixture reaches hard-crack stage at 305 degrees F (152 degrees C), 10 to 15 minutes. Remove from heat.
Quickly stir baking soda into brittle mixture until fully incorporated. Pour brittle onto the prepared baking sheet.
Stretch candy out by lifting and pulling from the edges using forks as the candy cools. Cool completely before breaking into pieces.
