I have hunted with divers in the marsh and had fantastic results. It was in the late season, and the guy put the divers on one side and the mallards on the other. We just absolutely smoked them that day (it was also my first duck hunt over decoys). The black on the bluebills really stands out from above, and the ducks can see them from along ways off. I have seen guys paint bleach bottles black to make the spread more visible from a distance.