Is the Gulf of Mexico part of the Atlantic Ocean?

The Gulf of Mexico is considered a marginal sea of the Atlantic Ocean. The gulf was considered part of the Atlantic Ocean until the 1540s, when it was named the Seno Mexicano by Spain.

The Gulf of Mexico is the ninth-largest body of water in the world with a surface area of approximately 600,000 square miles. This oceanic basin is surrounded by North America to the north, Mexico to the south and west, and the Caribbean Sea and Cuba to the southeast. It is sometimes to referred to as the "Mediterranean of the Americas" because it shares common traits with the Mediterranean Sea, another marginal sea of the Atlantic Ocean.