**Prepare the Cake:**

Preheat your oven to 350°F (175°C). Prepare the white cake mix according to package instructions, using water, oil, and eggs. Pour the batter into a greased 9x13-inch baking dish. Bake according to the package directions, usually 25-30 minutes, or until a toothpick inserted in the center comes out clean. Let the cake cool in the pan for about 10 minutes.

**Poke the Cake:**

Once the cake has cooled slightly, use a fork or the handle of a wooden spoon to poke holes all over the top of the cake, about 1 inch apart. Be sure not to poke all the way through the cake, just deep enough to create pockets for the cranberry sauce.

**Prepare the Cranberry Filling:**

In a small saucepan, combine the cranberry sauce, water, and sugar. Heat over medium heat, stirring occasionally, until the sugar is dissolved and the mixture is smooth. Let it simmer for 2-3 minutes to thicken slightly.

**Fill the Cake:**

Pour the warm cranberry mixture evenly over the top of the cake, making sure the sauce sinks into the holes. Let the cake absorb the cranberry sauce and cool completely.

**Make the Whipped Topping:**

In a mixing bowl, combine the heavy whipping cream, powdered sugar, and vanilla extract. Whip with an electric mixer on medium-high speed until soft peaks form.

**Top the Cake:**

Spread the whipped topping evenly over the cooled cake, covering it completely.

**Chill and Serve:**

Refrigerate the cake for at least 2 hours before serving to allow the flavors to meld and the topping to set. Slice and serve chilled.