Preheat oven to 350 degrees and spray a 9x13-inch baking dish with baking spray with flour.
In a large bowl, use a hand-held electric mixer to beat cake mix, water, vegetable oil, egg whites, and lime zest on LOW for 30 seconds.Beat on medium for 2 minutes.
Transfer batter to prepared baking dish.Bake for 25 to 30 minutes.
Let cool for 10 minutes and then poke holes in cake with the back of a wooden spoon.
Place cherry gelatin in a bowl and pour boiling water into bowl. Stir until dissolved.Slowly pour into holes.Cover and refrigerate at least 4 hours.
Spread Cool Whip on top and decorate with lime slices and maraschino cherries. Serve.