Containment dome

"The containment system is an apparatus that would essentially hover over a compromised well funneling escaping oil, gas and water into this dome," Smith said.

Because hydrocarbons are lighter than water, the containment dome became buoyant as it filled with oil and gas while BP tried to lower it.

BP engineers told Lynch that they had "lost the cofferdam" as the dome, full of flammable material, floated up toward the ships on the ocean surface.

Averting a potential disaster, the engineers were able to regain control of the dome and move it to safety on the sea floor.

In the wake of the cofferdam's failure, one high-level government official recalled Andy Inglis, BP's Chief Executive of Exploration and Production, saying with disgust, "If we had tried to make a hydrate collection contraption, we couldn't have done a better job".