Atlantic Ocean, the world's second largest body of water. Its area, including all connecting seas and gulfs, is about 33,420,000 square miles (86,557,000 km2), almost 24 per cent of the world's oceanic area. The main body has an area of nearly 32,000,000 square miles (82,880,000 km2).

The Atlantic is bounded on the east by Europe and Africa, and on the west by the Americas. To the north, it merges with the Arctic Ocean; to the south, it extends to Antarctica. The Equator is the dividing line between the North and South Atlantic.

Among the principal bodies of water adjoining the Atlantic are the Gulf of St. Lawrence, the Gulf of Mexico, and the Caribbean Sea on the west and the Baltic, North, and Mediterranean seas on the east.