That would be the Rio Grande river.
No body of water separates the US. from Mexico
Lake Erie
No. The Gulf of California is a body of water on the west of Mexico which separates the Baja California Peninsula (south of the US state of California) from the mainland Mexico. The Gulf of Mexico is on the southeastern US and east of Mexico, and US states such as Florida, Louisiana and Texas have shores on that body of water.
The Atlantic Ocean.
I'm guessing you want the Gulf of Mexico, since that separates the US from Mexico (to some extent, though the Rio Grande does that more thoroughly), Puerto Rico, and other Spanish-speaking islands in the Caribbean. ><><><><><>< Not Mexico, and Puerto Rico is not a country (it is a Commonwealth of the US) But the Gulf does separate the US from Cuba.
None. There is only the man-made border that separates the US from Mexico.
The Northern Atlantic
The body of water that separates The Bahamas from the United States is the Florida Straits. This narrow body of water lies between the southeastern coast of Florida and the northernmost islands of The Bahamas. It is known for its deep waters and is an important maritime route.
The Gulf of Mexico.
The Gulf of Mexico.
Mexico and Panama
There are two of them: The Pacific Ocean and the Gulf of Mexico.