On the eve of the six-month anniversary of the Deepwater Horizon oil disaster, a submarine piloted by Greenpeace Oceans director John Hocevar is taking marine scientist Steve Ross of University of North Carolina Wilmington on a journey to the floor of the Gulf of Mexico, to investigate how deep sea corals have been impacted by oil and dispersants. The two seater submarine is being deployed to depths of 1750ft (535m) from the Greenpeace ship Arctic Sunrise, just to the north of the Macondo wellhead, in the closing leg of a three-month expedition to study the environmental aftermath of the oil spill. The expedition is part of Greenpeace's ongoing work to protect the Gulf and support research to expose the full extent of the spill.