Deepwater Horizon Explosion
The Deepwater Horizon oil rig exploded, causing the largest marine oil spill in history
April 20, 2010
An Explosion on the Gulf
On April 20, 2010, the Deepwater Horizon oil rig, operated by BP in the Gulf of Mexico, experienced a massive blowout. A surge of natural gas shot up the drill column, ignited, and exploded, killing 11 workers and injuring 17 others. The rig burned for two days before sinking to the seafloor. The blowout preventer, a critical safety device meant to seal the well in an emergency, failed. Oil began gushing from the Macondo well at the bottom of the Gulf, roughly a mile below the surface. What followed was the largest accidental marine oil spill in history, lasting 87 days before the well was finally capped.
Millions of Gallons Released
Before the well was sealed in July 2010, approximately 4.9 million barrels — over 200 million gallons — of crude oil flowed into the Gulf of Mexico. Oil washed onto beaches and marshes across Louisiana, Mississippi, Alabama, and Florida. Fisheries were closed, tourism collapsed, and wildlife along the coast suffered. Thousands of sea turtles, dolphins, birds, and fish died. BP attempted to stop the flow with multiple failed techniques before finally succeeding with a relief well. The company also sprayed millions of gallons of chemical dispersants to break up the oil, a decision that itself drew scientific and public concern about environmental harm.
Accountability and Reform
BP ultimately agreed to pay more than $65 billion in fines, penalties, and cleanup costs — the largest corporate settlement in U.S. history at the time. Several BP executives faced criminal charges. The disaster led to significant reforms in offshore drilling safety regulations, including stricter requirements for blowout preventers and emergency response plans. A presidential commission found that the accident resulted from a series of decisions by BP, its contractors, and the regulatory agency overseeing offshore drilling that prioritized cost savings over safety. The Gulf ecosystem has shown partial recovery in the years since, but scientists continue to study its long-term effects. Use our date calculator to see how long ago this disaster occurred.