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 basin subsidence in the central region, as well as heavy sedimentation around the Florida Platform and Northern Gulf of Mexico. While a few intrusive igneous formations found as far south as Mexico City are dated to the Late-Jurassic or Early Cretaceous, the Gulf of Mexico during that time was relatively devoid of igneous activity. It wasn't until the Late Mesozoic that low-volume yet widespread volcanism occurred along the Western and Northwestern margins of the Gulf of Mexico, leaving the Yucatan Peninsula with an extremely alkali volcanic field in the subsurface. The volcanism is believed to have been activated along ancient plate