Oil giant BP had its international headquarters besieged by inflatable sea creatures as environmentalists protested over a forthcoming drilling project.
Greenpeace marched on the central London office as BP prepares to search for oil near a coral reef off the coast of South America next year.
Giant inflatable marine life including jellyfish and starfish were paraded along The Mall and past Trafalgar Square to reach the building shortly after 8am.
Signs reading "BP: Back off the Amazon Reef" were held up alongside the colourful procession.
Activists said they intended to remain camped outside BP, in St James's Square, for several hours on Monday morning.
Greenpeace said the exploratory drilling work, due to begin near the recently discovered Amazon Reef, risks an oil spill which could prove catastrophic for sea life.