While there have been many oil spills in the Gulf of Mexico in past decades, seven stand out for the amount of oil spilled, duration of the spill response, and/or resulting environmental impact.

Deepwater Horizon: The Deepwater Horizon oil spill is the largest marine oil spill in history, and was caused by an explosion on the Deepwater Horizon offshore oil platform about 50 miles southeast of the Mississippi River delta on April 20, 2010. Most of the 126 workers on the platform were safely evacuated, and a search and rescue operation began for 11 missing workers. The Deepwater Horizon sank in about 5,000 feet (1,500 m) of water on April 22, 2010. On April 23 the U.S. Coast Guard suspended the search for missing workers who are all presumed dead. After a series of failed efforts to plug the leak, BP said on July 15 that it had capped the well, stopping the flow of oil into the Gulf of Mexico for the first time in 86 days. The BP spill is by far the world's largest accidental release of oil into marine waters. The U.S. goverment estimated that about 4.9 million barrels of oil were released, of which about 800,000 barrels were captured by containment efforts.

Ixtoc: The second-largest largest oil spill in North America occurred in the Gulf of Mexico. The 200-foot-deep exploratory well, Ixtoc I, blew out on June 3, 1979, in the Bay of Campeche, Mexico, releasing 10,000 - 30, 000 barrels (0.4 - 1.2 million gallons) per day for nine months. Nearly 500 dispersant air sorties were flown in Mexico. Manual cleanup in Texas was aided by storms. Though the blowout preventer (BOP, valve designed to seal off a wellhead) failed, injection of metal and concrete balls into the well slowed the release. By the time the well was brought under control in March 1980 by drilling two relief wells to relieve pressure, an estimated 113 million to over 300 million gallons of oil had spilled (10 times the amount of oil spilled by the Exxon Valdez). Oil travelled 800 miles to the north, oiling more than 150 miles of shoreline in Texas and unknown miles of shoreline in Mexico. [READ MORE]