I saw these somewhere, and had to try them. I made this batch for my niece and her friends for a 4th of July gathering.
I used buttercream frosting and blue food coloring for the water. Then I stuck teddy grahams on little lifesaver innertubes, and stuck an umbrella next to them. You can also cover the cupcakes in graham cracker crumbs, to look like sand. I'll try those next time.
They're fun and easy, and the kids loved them (as did the adults). haha :D