Q: Context: The Gulf of Mexico (Spanish: Golfo de México) 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, or sometimes the "south coast", in juxtaposition to the Great Lakes region being the "north coast."

Question: what type of landform is the gulf of mexico? Let's give stream of consciousness first:
To answer this question, we should know that: The Gulf of Mexico (Spanish: Golfo de México) is an ocean basin and a marginal sea of the Atlantic Ocean, largely surrounded by the North American continent. Therefore, the final answer is an ocean basin and a marginal sea of the Atlantic Ocean.