For this cake, I put two mermaids on a beach with waves and water beneath them. I found chocolate candies that looked like rocks and shells and my local grocery store, and the beach is crushed up graham crackers. This fish and coral are flavored tootsie rolls.
My daughter had a 2nd party for her friends from school. For them I made these simple cupcakes with wave like frosting and cup covers and paper mermaids on sticks. I can't take the credit for the design of the mermaids or cupcake holders...the internet is full of wonderful ideas if you have the motivation and energy to tackle them.