Special equipment: Pastry bag; large star tip, 3 paper umbrellas, jellied octopus candy, chocolate seashell candy
Place cake, wide side down, on serving platter. Fill hole in center of cake with marshmallows. Spread 1 1/2 containers of frosting evenly over top of sides of cake to coat completely. Stir food coloring, I drop at a time, into remaining 1/2 container of frosting until desired color is achieved. Transfer blue-colored frosting to pastry bag fitted with star tip. Pipe thick line of frosting around base of cake. Starting at base of cake and swirling in semicircular upward motion, drag wooden skewer through blue-colored frosting to form wave design. Arrange umbrellas on top. Arrange jellied candy octopus and chocolate seashells decoratively on cake. Sprinkle coconut around the base of cake.