Preheat oven to 350°F (175°C) and grease a 9x13 inch baking pan.
In a large bowl, combine cake mix, water, oil, and eggs; beat for 2 minutes or until smooth.
Pour batter into the prepared pan and bake for 30 minutes or until a toothpick comes out clean.
Allow the cake to cool for 20 minutes.
Using the handle of a wooden spoon or a large fork, poke holes throughout the top of the cake at 1-inch intervals.
In a medium bowl, dissolve the strawberry gelatin powder in 1 cup of boiling water, then stir in 1/2 cup of cold water.
Slowly pour the gelatin mixture over the cake, ensuring it flows into the holes.
Cover and refrigerate for at least 3 hours to allow the gelatin to set.
Spread the thawed whipped topping evenly over the top of the cake.
Garnish with sliced fresh strawberries before serving.