The Deepwater Horizon oil spill (also referred to as the BP oil spill, the BP oil disaster, the Gulf of Mexico oil spill, and the Macondo blowout) began on 20 April 2010 in the Gulf of Mexico on the BP-operated Macondo Prospect. It claimed eleven lives and is considered the largest accidental marine oil spill in the history of the petroleum industry, an estimated 8% to 31% larger in volume than the previously largest, the Ixtoc I oil spill. Following the explosion and sinking of the Deepwater Horizon oil rig, a sea-floor oil gusher flowed for 87 days, until it was capped on 15 July 2010. The total discharge has been estimated at 4.9 million barrels (210 million US gal; 780,000 m3).
A massive response ensued to protect beaches, wetlands and estuaries from the spreading oil utilizing skimmer ships, floating booms, controlled burns and 1.84 million US gallons (7,000 m3) of Corexit oil dispersant. After several failed efforts to contain the flow, the well was declared sealed on 19 September 2010. Some reports indicate the well site continues to leak. Due to the months-long spill, along with adverse effects from the response and cleanup activities, extensive damage to marine and wildlife habitats, fishing and tourism industries, and human health problems have continued through 2013. Three years after the spill, tar balls could still be found on the Mississippi coast. In July 2013, the discovery of a 40,000 pound tar mat near East Grand Terre, Louisiana prompted the closure of waters to commercial fishing.