Greenpeace activist in the foreground, behind him activists chained to a mooring rope of oil tanker 'Byzantio' in the port of Rotterdam. The banner at the bow reads "Oil Hazard". 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.