Gulf of Mexico Gulf of Mexico The Gulf of Mexico () is an ocean basin and a marginal sea of the Atlantic Ocean, largely surrounded by the North American continent. It is bounded on the northeast, north and northwest by the Gulf Coast of the United States, on the southwest and south by Mexico, and on the southeast by Cuba. The U.S. states of Texas, Louisiana, Mississippi, Alabama, and Florida border the Gulf on the north, which are often referred to as the "Third Coast", in comparison with the U.S. Atlantic and Pacific coasts. The Gulf of Mexico formed approximately 300 million years
Gulf of Mexico zone of uniformly thinned transitional crust, which is half the typical 40 kilometer thickness of normal continental crust. It was at this time that rifting first created a connection to the Pacific Ocean across central Mexico and later eastward to the Atlantic Ocean. This flooded the opening basin to create the Gulf of Mexico as an enclosed marginal sea. While the Gulf of Mexico was a restricted basin, the subsiding transitional crust was blanketed by the widespread deposition of Louann Salt and associated anhydrite evaporites. During the Late Jurassic, continued rifting widened the Gulf of Mexico and progressed to the