Preheat the oven to 350°F (175°C). Grease and flour a 9×13 inch baking pan.
In a large bowl, combine the yellow cake mix, water, vegetable oil, and eggs. Beat with an electric mixer 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 into the center comes out clean.
Remove the cake from the oven and let it cool completely in the pan on a wire rack.
Once cooled, use the handle of a wooden spoon or a fork to poke holes all over the surface of the cake.
In a medium bowl, prepare the instant vanilla pudding by whisking together the pudding mix and cold milk until thickened, about 2 minutes.
Spread the vanilla pudding evenly over the cake, filling the holes as much as possible.
Arrange the sliced bananas evenly over the pudding layer.
Dissolve the strawberry gelatin powder in 1 cup boiling water, stirring until completely dissolved. Let it cool to room temperature but not set.
Pour the cooled strawberry gelatin evenly over the bananas and pudding layer.
Repeat the process with the pineapple gelatin: dissolve in 1 cup boiling water, cool to room temperature, then carefully pour over the strawberry layer.
Repeat the process with the cherry gelatin: dissolve in 1 cup boiling water, cool to room temperature, then carefully pour over the pineapple layer.
Refrigerate the cake for at least 4 hours or until the gelatin layers are fully set.
In a chilled mixing bowl, beat the heavy whipping cream, powdered sugar, and vanilla extract on high speed until stiff peaks form.
Spread the whipped cream evenly over the set gelatin layer.
Sprinkle the chopped walnuts and halved maraschino cherries evenly over the whipped cream as decoration.
Keep the cake refrigerated until ready to serve. Cut into squares and serve chilled.