reporter: we headed out to the spot closest to the oil spill for a submarine ride to the gulf floor. it s pretty cold on this here boat. going about 40 or 50 miles an hour. roger that. roger. just a couple of miles that way is where the bp rig sank. technically it s still a crime scene. pretty cozy in here. reporter: the water laps over the hull as we rocket downwards 5,000 feet. we should be seeing a cacophony of life here. creatures dreamed up for a sci-fi movie. but on this moonscape there s nothing crawling around on the surface of the bottom. it s just worm cubes that are collapsed over. reporter: dr. mandy joy, oceanographer, is leading a national science foundation expedition to the heart of the spill and the grave of many a sea creature. there s a lot of dead worms on the bottom. reporter: we course through the water like some alien body. inside this titanium sphere,