The Atlantic Ocean is the second-largest ocean basin on Earth. Its S-shaped geography, which separates the Americas from Europe and Africa, makes defining a single, exact width a complex task. The distance between the continents changes dramatically along its length, ranging from its narrowest chokepoint to a broad expanse in the Southern Hemisphere. This variation in size reflects the dynamic geological forces that continually shape its boundaries.
The Key Measurement of Width
The width of the Atlantic Ocean is highly variable, with its maximum and minimum measurements occurring in different latitudes. The narrowest distance across the main ocean body occurs in the South Atlantic, specifically between the coastline of Brazil and the coast of Liberia in West Africa. At this point, the ocean is approximately 1,770 miles (2,848 kilometers) wide.
The ocean’s widest point is located much farther north, where the basin expands significantly. This maximum width stretches between the eastern coast of the United States and the Iberian Peninsula or Northern Africa. The distance across this broad section reaches about 2,848 miles (4,583 kilometers). The overall average width of the Atlantic is often cited in general geography texts as being around 3,300 miles (5,300 kilometers).
Geographic Boundaries and Total Area
The ocean covers an area of approximately 32.87 million square miles (85.133 million square kilometers), excluding its marginal seas. Including these dependent bodies of water, the total area increases to about 41.1 million square miles (106.46 million square kilometers).
The ocean’s boundaries extend from the Arctic Ocean in the north to the Southern Ocean near Antarctica in the south. The separation between the North and South Atlantic is generally considered to be at the Equator. In the south, the Atlantic meets the Pacific Ocean at the Drake Passage and the Indian Ocean south of Cape Agulhas along the 20° E meridian.
The Geological Reason for Expansion
The Atlantic Ocean is actively and continuously widening. This ongoing expansion is dictated by the Mid-Atlantic Ridge (MAR), an underwater mountain range. The MAR represents a classic divergent plate boundary, where the tectonic plates are pulling apart from one another.
As the plates separate, magma from the Earth’s mantle rises to fill the resulting gap, solidifying to form new oceanic crust in a process known as seafloor spreading. The rate of this spreading is relatively slow compared to other ocean basins, which is why the Mid-Atlantic Ridge is classified as a slow-spreading center. The continents bordering the Atlantic are moving away from the ridge at a rate of approximately 1 to 2 centimeters (0.4 to 0.8 inches) per year. This means the entire ocean basin is widening by about 2.5 centimeters (1 inch) annually, a rate comparable to the growth of a human fingernail.