Greenpeace boards and occupies the Belgian dredger Gallilei 2000 to prevent the dumping of TBT sludge from Zeebrucker harbour. Activists chain themselves or place themselves in the sludge in protective clothing and breathing apparatus. The levels of TBT in the sludge are well above the legal requirements. Tributyltin (TBT) is a toxic processed in many ship paints to prevent the growth of alga and sea acorns to the ship's hull. TBT damages sea life. Female shellfish develop male sexual characteristics and become infertile. Because of this the sea whelks have already disappeared in the Wadden Sea. The action is part of the Greepeace 'Down to Zero' toxics campaign.