Preheat the oven to 350 degrees F (175 degrees C).

Melt and spread 1/2 cup margarine in the bottom of a 9x13-inch pan. Sprinkle coconut and pecans evenly over the bottom of the pan; set aside.

Prepare cake batter by adding cake mix, water, oil, and eggs together in a large bowl. Stir until combined. Pour batter over coconut and pecans in pan.

Melt cream cheese and remaining 1/2 cup margarine in a saucepan over low heat. Stir in confectioners' sugar until mixture is smooth. Spoon cream cheese mixture randomly over top of cake batter.

Bake in the preheated oven until a toothpick inserted into the center of the cake comes out clean, 35 to 40 minutes. Allow to cool and serve from the pan.