Instead of using environmentally-hazardous tin-based paints on the bottoms of vessels, the ships' hulls are brushed by divers several times each year.
The diving company DG Diving Group Viking Line uses a patented, environmentally-sound brushing method that it has developed inhouse. This method involves collecting all growths loosened from the bottoms of vessels during brushing into a separate container, which is then brought ashore for further treatment. The waste is used in part to make biogas.