Which area of Mexico is almost entirely at sea land?

Question

Yuacatan Peninsula?

What is The name given given to the mountain range that covers most of mexico
Sierra Madre Occidental

Answer 1

I'm not sure I understand your first question. What about the Baja Peninsula?

I think it would be more accurate to say that this mountain range is called the Sierra Madre. Note that the Sierra Madre Oriental parallels Sierra Madre Occidental in the eastern part of the country.