Greenpeace is a non-governmental organization for the protection and conservation of the environment. Greenpeace uses direct action, lobbying and research to achieve its goals. Greenpeace has a worldwide presence with national and regional offices in 46 countries, which are affiliated to the Amsterdam-based Greenpeace International. The global organization receives its income through the individual contributions of almost 3 million financial supporters.

Greenpeace evolved from the peace movement and anti-nuclear protests in Vancouver, British Columbia in the early 1970's. On September 15, 1971, the Don't Make a Wave Committee sent the eighty foot halibut seiner Phyllis Cormack, renamed Greenpeace for the protest, from Vancouver, to oppose United States testing of nuclear devices in Amchitka, Alaska. While the boat never reached its destination and was turned back by the US military, this campaign was deemed the first using the name Greenpeace The organisation itself dates its birth to the first protest. The focus of the organization later turned from anti-nuclear protest to other environmental issues: whaling, bottom trawling, global warming, old growth, nuclear power, and genetically modified organisms.

Campaigns of Greenpeace have raised environmental issues to public knowledge and influenced both the private and the public sector, but the organisation has also received criticism for its methods and motives.

On its official website, Greenpeace defines its mission as the following:

Greenpeace is an independent global campaigning organisation that acts to change attitudes and behaviour, to protect and conserve the environment and to promote peace by:

• Catalysing an energy revolution to address the number one threat facing our planet: climate change.
• Defending our oceans by challenging wasteful and destructive fishing, and creating a global network of marine reserves.
• Protecting the world’s remaining ancient forests which are depended on by many animals, plants and people.
• Working for disarmament and peace by reducing dependence on finite resources and calling for the elimination of all nuclear weapons.
• Creating a toxic free future with safer alternatives to hazardous chemicals in today's products and manufacturing.
• Campaigning for sustainable agriculture by encouraging socially and ecologically responsible farming practices.

Since Greenpeace was founded, seagoing ships have played a vital role in its campaigns.

In 1978, Greenpeace launched the original Rainbow Warrior, a 40-metre (130 ft), former fishing trawler named for the Cree legend that inspired early activist Robert Hunter on the first voyage to Amchitka. Greenpeace purchased the Rainbow Warrior (originally launched as the Sir William Hardy in 1955) at a cost of £40,000. Volunteers restored and refitted it over a period of four months.

First deployed to disrupt the hunt of the Icelandic whaling fleet, the Rainbow Warrior would quickly become a mainstay of Greenpeace campaigns. Between 1978 and 1985, crew members also engaged in non-violent direct action against the ocean-dumping of toxic and radioactive waste, the Grey Seal hunt in Orkney and nuclear testing in the Pacific. Japan's Fisheries Agency has labeled Greenpeace ships as "anti-whaling vessels" and "environmental terrorists".

In May 1985, the vessel was instrumental for 'Operation Exodus', the evacuation of about 300 Rongelap Atoll islanders whose home had been contaminated with nuclear fallout from a US nuclear test two decades ago which had never been cleaned up and was still having severe health effects on the locals.

Later in 1985 the Rainbow Warrior was to lead a flotilla of protest vessels into the waters surrounding Moruroa atoll, site of French nuclear testing. The sinking of the Rainbow Warrior occurred when the French government secretly bombed the ship in Auckland harbour on orders from François Mitterrand himself. This killed Dutch freelance photographer Fernando Pereira, who thought it was safe to enter the boat to get his photographic material after a first small explosion, but drowned as a result of a second, larger explosion. The attack was a public relations disaster for France after it was quickly exposed by the New Zealand police. The French Government in 1987 agreed to pay New Zealand compensation of NZ$13 million and formally apologised for the bombing. The French Government also paid 2.3 million compensation to the family of the photographer.

In 1989 Greenpeace commissioned a replacement vessel, also named the Rainbow Warrior, which remains in service today as the flagship of the Greenpeace fleet.

In 1996 the Greenpeace vessel MV Sirius was detained by Dutch police while protesting the import of genetically modified soybeans due to the violation of a temporary sailing prohibition, which was implemented because the Sirius prevented their unloading. The ship, but not the captain, was released half an hour later.

In 2005 the Rainbow Warrior II ran aground on and damaged the Tubbataha Reef in the Philippines while she was, ironically, on a mission to protect the very same reef. Greenpeace was fined $7,000 USD for damaging the reef and agreed to pay the fine, although it said that the Philippines government had given it outdated charts.