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) was an oil spill in the Gulf of Mexico on the BP-operated Macondo Prospect, considered the largest accidental marine oil spill in the history of the petroleum industry, estimated to be between 8% and 31% larger in volume than the earlier Ixtoc I oil spill. Following the explosion and sinking of the Deepwater Horizon oil rig, which claimed 11 lives, a sea-floor oil gusher flowed unabated for 87 days, until it was capped on 15 July 2010. The total discharge is 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 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.