The Greenpeace ship, MY Arctic Sunrise, sails in the deep waters in the Gulf of Mexico, six nautical miles from the site of the Deepwater Horizon oil spill. Independent scientists start their third set of tests at a depth of 1,300 meters. Greenpeace, partnered with teams of independent scientists, has been investigating the environmental effects of the oil spill and toxic dispersants used to break up the four million barrels of crude oil spilled in the worst environmental disaster in United States history.