PREPARE and bake cake mix in 13x9-inch baking pan as directed on package. Cool completely. Invert cake onto large platter; remove pan. Using a serrated knife, cut and scoop out a shallow rectangle from center of cake, leaving a 2-inch border of cake on all sides and a thin layer of cake on the bottom. Reserve removed cake for snacking or other use. STIR boiling water into dry gelatin mix in large bowl at least 2 min. until completely dissolved. Stir in cold water. Refrigerate 1-1/4 hours or until slightly thickened (consistency of unbeaten egg whites). (Or, see Tip below for quicker set method.) Pour thickened gelatin into center of cake. Refrigerate 3 hours or until set. FROST borders of cake with whipped topping. Decorate with remaining ingredients as desired to resemble a swimming pool. Store leftover cake in refrigerator.
KRAFT KITCHENS TIPS
Fun Idea Insert bite-size fish-shaped and octopus-shaped chewy fruit snacks into gelatin "pool" before refrigerating for an added treat!
Shortcut For a quick-set gelatin, simply add 4 cups ice cubes to the dissolved gelatin mixture in place of the 1 cup cold water; stir 8 min. or until gelatin begins to thicken (spoon drawn through leaves a definite impression). Remove any unmelted ice. Pour thickened gelatin into center of cake; continue as directed.
RECIPE COURTESY OF KRAFT FOODS