A small pollution containment chamber

A small pollution containment chamber, known as the "top hat," is lowered into the Gulf of Mexico May 11, 2010, by the motor vessel Viking Poseidon. The chamber is being used in an attempt to contain the oil spill caused by the explosion of the mobile offshore drilling unit Deepwater Horizon. (DoD photo by Petty Officer 3rd Class Patrick Kelley, U.S. Coast Guard/Released)