Preheat the oven to 350°F (175°C). Grease and flour a 9x13-inch baking pan.
In a large mixing bowl, combine the cake mix, water, vegetable oil, and eggs. Beat on medium speed for 2 minutes until well blended.
Pour the batter into the prepared baking pan and bake for 30-35 minutes, or until a toothpick inserted in the center comes out clean. Let the cake cool completely in the pan.
Once the cake is cool, use the handle of a wooden spoon to poke holes all over the top of the cake, about 1 inch apart.
In a medium bowl, dissolve the strawberry Jell-O in 1 cup of boiling water. Stir until completely dissolved. Pour evenly over the cake, allowing it to seep into the holes. Refrigerate for 30 minutes.
In another medium bowl, dissolve the blueberry Jell-O in 1 cup of boiling water. Stir until completely dissolved. Pour evenly over the cake after the strawberry layer has set. Refrigerate for an additional 30 minutes.
Once the Jell-O layers are set, spread the whipped topping evenly over the top of the cake. Garnish with fresh strawberries and blueberries.
Slice and serve chilled.