The Greenpeace ship Esperanza sails down the River Thames. London's Tower Bridge can be seen in the background.
The Esperanza is in London to launch one of Greenpeace's biggest ever expeditions: an almost year-long pole to pole voyage from the Arctic to the Antarctic, to highlight the many threats facing the oceans and to campaign for a Global Ocean Treaty covering all seas outside of national waters.
The 'Protect the Oceans' expedition will see scientists and campaigners team up to research the threats of climate change, overfishing, plastic pollution, deep sea mining and oil drilling.