Oil tanker 'Byzantio' with Greenpeace tent chained to a mooring rope and a banner that reads "Oil Hazard" at the bow in the port of Rotterdam. Greenpeace activists attempt to occupy the single-hulled oil tanker 'Byzantio', sister ship of the "Prestige" a single hull tanker that polluted the Galician coast earlier this month. Greenpeace is highlighting the fact that the vessel is unsafe with its cargo of 50,000 tons of oil.