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 central thin transitional and oceanic crust. Because subsidence occurred faster than sediment could fill it, the Gulf of Mexico expanded and deepened. Later, loading of the crust within the Gulf of Mexico and adjacent coastal plain by the accumulation of kilometers of sediments during the rest of the Mesozoic and all of the Cenozoic further depressed the underlying crust to its current position about 10–20 km below sea level. Particularly during the Cenozoic, thick clastic wedges built out the continental shelf along the northwestern and northern margins of the Gulf of Mexico. To the east, the stable Florida platform was