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) water in 1962; and in a thousand feet of water in 1979. "By 1970, the technology existed to drill in 2,000 feet of water and actual exploratory drilling was taking place at 1,400 feet." By 2009, more than 70% of Gulf of Mexico oil production came from wells drilled in depths greater than , almost double from the percentage ten years ago. The deepest water depth in which a discovery has been made is , at Lloyd Ridge 370 (Diamond). The federal government has not allowed drilling in federal waters in the eastern Gulf of Mexico, which includes offshore Florida