Preheat oven to 350°F (175°C).

Grease a jelly roll pan.

In a large bowl, combine cake mix, water, vegetable oil, and eggs.

Mix until smooth.

Pour batter into the prepared jelly roll pan.

Bake for 20 minutes, or until a toothpick inserted into the center comes out clean.

Let the cake cool completely.

In a separate bowl, mix cream cheese until smooth.

Add vanilla pudding mix and milk.

Beat until smooth.

Gently fold in crushed and drained pineapple.

Spread the cream cheese mixture evenly over the cooled cake.

Spread Cool Whip over the cream cheese layer.

If desired, sprinkle with coconut.

Refrigerate for at least 20 minutes before serving.