Preheat oven to 350°.
In a large bowl, mix together the cake mix, water, eggs, oil and can of crushed pineapple (juice included). Pour into a greased 9X13 pan and bake for 28-33 minutes or until a toothpick inserted in the middle of the cake comes out clean.
Let the cake cool for about 10-15 minutes and then poke holes all over the top of cake with a fork. Just poke the fork down about halfway through the cake and try to make the holes evenly spaced.
Mix the sweetened condensed milk and pina colada mix together. Pour evenly over the cake.
After the cake is completely cooled, place plastic wrap over the top and refrigerate.
To make the topping, mix the instant pudding and crushed pineapple together in a large bowl. Fold in the Cool Whip and mix until well combined and then spread on top of the chilled cake. Cover and refrigerate until ready to serve. Cake is best if eaten within 2-3 days.