BP

On April 20, 2010, while drilling oil giant BP's Macondo well in the Gulf of Mexico, the crew lost control of the well. There was a "blowout" that released gas and oil, leading to an explosion that killed 11 workers.

The Deepwater Horizon rig was destroyed and sank two days later. Over the next nearly three months, 210 million gallons of oil flowed from the well into the Gulf.

It was one of the biggest environmental disasters in U.S. history.

Jet fuel-guzzling Delta Air Lines and fossil fuel-pumping BP are vowing to go carbon neutral.