Line up the cupcakes, 4 to a row on the cake board.
Add a small amount of white buttercream to the bottom of each cupcake to anchor them in place on the board.
Divide up the buttercream and make one bowl of icing blue by adding 2 drops of the blue food coloring to the icing, Mix it to blend the blue.
Fill a piping bag with the blue buttercream, cut off the tip of the piping bag and pipe zig zag rows of buttercream.
Use an offset spatula or a spoon to create “waves” on the cupcakes.
If writing on the pull apart, fit a piping bag with a #5 icing tip and fill with white buttercream and write your message.
Add a thick wide line of white buttercream around all 4 sides of the pull apart cake. Spread out the icing with the offset spatula or spoon.
Top the icing around the cupcakes on the cake board with brown sugar to create the illusion of “sand”. Press the brown sugar into the buttercream so it doesn’t fall off when moving the pull apart cake.