Gulf of Mexico numerous bays and smaller inlets. A number of rivers empty into the gulf, most notably the Mississippi River and Rio Grande in the northern gulf, and the Grijalva and Usumacinta rivers in the southern gulf. The land that forms the gulf's coast, including many long, narrow barrier islands, is almost uniformly low-lying and is characterized by marshes and swamps as well as stretches of sandy beach. The Gulf of Mexico is an excellent example of a passive margin. The continental shelf is quite wide at most points along the coast, most notably at the Florida and Yucatán Peninsulas. The shelf
Offshore oil and gas in the Gulf of Mexico (United States) blowout) began on April 20, 2010, in the Gulf of Mexico on the BP-operated Macondo Prospect. Killing eleven people, it is considered the largest marine oil spill in the history of the petroleum industry and estimated to be 8% to 31% larger in volume than the previous largest, the Ixtoc I oil spill. In 2012, federal leases in the Gulf of Mexico produced of oil, which made up 19.5% of all U.S. oil production that year, and more than that of any U.S. state other than Texas. The 2012 production was less than the in 2009; however, due to new