Preheat oven to 350 degrees F.
Combine cake mix and 1/2 cup cold water. Beat 1 minute. Beat in eggs, water, vanilla and oil. Mix well. Place ice cream cones in muffin tins or on cookie sheet and fill each 1/2 full with batter (they can be filled 2/3 if tin foil is funneled around tops of cones so that batter can rise above the rim of the cone without spilling over). Bake 15 minutes or until cake springs back to the touch. Frost and decorate when cooled.