Greenpeace's Rainbow Warrior III, one of the world's most famous symbols of environmental activism, arrived in London on Tuesday afternoon after making its maiden voyage to Amsterdam.
It is just over 30 years ago that the first Rainbow Warrior launched from the Thames and went on to define environmental campaigning for a generation.
The original, a converted British fishing trawler, was blown up by French special forces in New Zealand in 1985, in an attempt to stop the Greenpeace campaign against French H-bomb tests in its Pacific colonies.
The second, which was also a refit of an old boat, has now been donated as a hospital ship in Bangladesh.
Sailing up the Thames, the latest ship is a slick operation. At 838 tonnes, with a sail capacity of over 1200 sq metres, it is the first Rainbow Warrior to have been designed and specifically built for the purpose of promoting environmental causes.
The ships are used to raise awareness of the many environmental injustices of the time, from nuclear testing in the Pacific Islands to the dumping of hazardous chemicals at sea and deforestation in the Amazon.
The Rainbow Warrior III is the first to have been built specifically for Greenpeace's environmental campaigns, and is one of the most environmentally friendly boats in the world. It has an energy efficient electric engine, uses heat from the engine for hot water and heating, and has on-board bio waste treatment, so that it is not discharged into the sea.
Talking to The Huffington Post UK from West India dock, where the boat and its crew arrived, John Sauven, Executive Director of Greenpeace, explained that this purpose-built ship is a "big statement of our values and the new technology we will be harnessing to solve environmental issues".
Greenpeace has had to adapt to the new world of environmental activism, over the past 40 years. But many of the issues have remained a constant as they still tackle climate change, deforestation and sustainable fishing.
Sustainable fishing has become a particular area of contention for tactics from different environmental groups.
Whilst newcomers such as the Sea Shepherd now take a more confrontational approach, Greenpeace remains attached to its non-violent action, as Sauven explained.
"We have to say each to their own tactics. We think strategically to fight our battles and we feel that we are winning the battle against whaling by talking to the Japanese themselves.
"Sea Shepherd are confronting Japanese people aggressively and it is exacerbating nationalism, and actually making it more difficult".
Over the next six days the Rainbow Warrior will be moored at West India Dock on the Thames, where it will play host to thousands of Greenpeace supporters, as well as local school children and special guests.