The Deepwater Horizon oil spill started with a blowout and explosion on April 20, 2010 at BP's Macondo Prospect drilling site. The gusher continued for 87 days and was declared capped on Sept. 19, 2010. There is evidence, however, that oil continues to seep from the site as of 2014.
The Deepwater Horizon oil rig exploded while drilling after an unanticipated bubble of methane gas rose to the surface from the new well. Of 126 crew members, 11 went missing and are presumed to have died in the explosion. About 4.9 million barrels of oil escaped from the well before it was finally capped. The primary cause of the spill is unclear as of 2014, but several contributing factors, from higher pressure in the well than anticipated to flawed cement used in the drilling and capping process, have been blamed.