From Texas Standard:
On April 20, 2010, the Deepwater Horizon oil rig exploded. Two days later, it crashed into the ocean. By mid-May, an underwater camera showed the broken pipe constantly gushing black liquid into the Gulf of Mexico.
As the oil spread, so did the panic. Crews tried several different methods to keep it from spreading across the Gulf and into sensitive ecosystems. Engineers tried everything from a containment dome to a “top kill” – sealing the pipe with cement. Nothing worked.