The Atlantic Ocean is down the middle of the Western and Eastern Hemisphere.
The division between the Western and Eastern hemisphere is called the Prime Meridian, located at 0° longitude. The Prime Meridian which is the middle of the Western and Eastern hemisphere passes through the Atlantic Ocean.
Four oceans are at least partially located in the Western Hemisphere: the Arctic (which encases the Arctic Circle at the northernmost points of the world), the Southern Ocean (which surrounds Antarctica at the southernmost points of the world), the Atlantic Ocean (which separates North and South America from Europe and Africa), and the Pacific.
The only ocean that is located entirely in the Eastern Hemisphere is the Indian Ocean.
