A sudden blowout of methane gas aboard the Deepwater Horizon drilling rig triggered explosions and fire, killing 11 crew members and sinking the platform two days later. The ruptured wellhead, a mile beneath the surface, gushed roughly 4.9 million barrels of oil over 87 days, devastating Gulf Coast ecosystems and fisheries and prompting sweeping changes to offshore drilling regulation.
The rig, owned by Transocean and leased by BP, was completing an exploratory well roughly 5,100 feet underwater when a surge of methane gas blew past faulty cement seals and shot up the drill column, igniting on the platform in a fireball visible for miles. Eleven crew members died in the initial blast; 115 others escaped, many by leaping into the Gulf, before the rig sank on April 22nd.
What followed was an environmental disaster measured in superlatives: the largest accidental marine oil spill in history, an estimated 4.9 million barrels leaking from the seafloor over three months before engineers finally capped the well with a specially engineered containment device. Oil fouled over 1,300 miles of coastline across five states, killed untold numbers of birds, dolphins, and sea turtles, and crippled the Gulf fishing and tourism economies for years.
Investigations found a cascade of failures, cost-cutting shortcuts on cement work, ignored pressure test warnings, and a blowout preventer that didn't work, resulting in BP paying over $65 billion in cleanup costs, fines, and settlements, the largest corporate payout in U.S. history at the time. The disaster reshaped offshore drilling oversight, though drilling in deep Gulf waters resumed within a few years.