This moderate-resolution mosaic of Italy shows the usual problems with cloud cover over the land, but also several problems which are more pronounced over the sea. The satellite used here has a wide angle of view, so it encounters a varying amount of atmospheric scattering, as well as reflection of sunlight off the surface of the water (sunglint) in parts of the image. Six images were chosen to minimise cloud cover over the land (centre), but each image has sunglint in a different location. By using a water mask derived from a digital map, we can apply different processing techniques to the land and sea, so as to preserve permanent water features such as shallows and river discharge plumes, but remove transient features such as sunglint (right).