BP was the oil company responsible for the 2010 Deepwater Horizon oil spill.
The disaster began on 20 April 2010 at BP’s Macondo prospect in the Gulf of Mexico. A blowout caused methane gas to surge up the well and ignite on the Deepwater Horizon drilling rig. The explosion killed 11 workers, injured 17 others and eventually sank the rig.
BP operated and principally developed the Macondo well, which is why the spill is commonly identified with the company. The well released an estimated 4.9 million barrels of oil before it was finally capped on 19 September 2010, making it the largest marine oil spill in petroleum-industry history.
Responsibility was shared in the technical and legal investigations. Transocean owned and operated the rig, while Halliburton performed cementing work. A U.S. judge nevertheless assigned 67% of the blame to BP, 30% to Transocean and 3% to Halliburton, reinforcing BP as the canonical quiz answer.