On what date in 2010 did the Deepwater Horizon oil spill begin in the Gulf of Mexico?

The Deepwater Horizon oil spill began on April 20, 2010, in the Gulf of Mexico. That evening, a blowout at BP’s Macondo exploration well caused methane gas to surge onto the Deepwater Horizon drilling rig, where it ignited in a series of explosions.

The rig was a semi-submersible vessel owned by Transocean and operated by BP. Eleven workers died and 17 others were injured. The platform burned for two days before sinking on April 22, leaving the damaged well leaking oil from the seafloor.

Although the accident began on April 20, the large oil slick was not identified until April 22. The leak continued for 87 days before the well was finally capped. Government estimates put the total release at approximately 4.9 million barrels of oil, making it the largest accidental marine oil spill in the history of the petroleum industry.

The dates in the wrong options reflect nearby events: April 22 was the day the rig sank and the slick was discovered, while April 25 was not the start of the disaster.