At its narrowest, the Atlantic Ocean spans roughly 1,770 miles (2,850 km) between the northeastern tip of Brazil and the west coast of Liberia. At its widest, the ocean stretches to more than 3,000 miles (4,800 km) across its midsection. That difference of over 1,200 miles between the slimmest and broadest crossings reflects the Atlantic’s distinctive S-shaped profile, a shape that has influenced everything from early aviation routes to the genetic isolation of marine species on opposite shores.
Where the Atlantic Is Narrowest
The shortest distance across the Atlantic lies in the tropical South Atlantic, between Cape São Roque on Brazil’s northeastern bulge and Cape Palmas on the coast of Liberia. That gap measures about 1,770 miles (2,850 km).1Encyclopædia Britannica. Atlantic Ocean If you look at a globe, the reason is easy to see: the eastward jut of South America and the westward curve of West Africa bring the two continents closer together here than at any other latitude. This is the spot where the two landmasses once fit together like puzzle pieces before the ancient supercontinent Pangea broke apart.
The narrowness of this crossing made it a natural target for early aviators. In 1922, Portuguese airmen Gago Coutinho and Sacadura Cabral became the first to fly from Europe to the South Atlantic, navigating the route with a modified sextant fitted with spirit levels to create an artificial horizon.2Open Journal of Applied Sciences. First Flight from Europe to the South Atlantic The relatively shorter distance across the South Atlantic made it a more feasible target for the fragile aircraft of the era, where every hundred miles of open water added serious risk.
Where It Is Widest
Moving north and away from the tropics, the Atlantic broadens considerably. Between Newfoundland and Ireland, the ocean stretches about 2,060 miles (3,320 km), and farther south it widens to more than 3,000 miles (4,800 km).1Encyclopædia Britannica. Atlantic Ocean The widest span falls roughly between the southeastern coast of the United States and the coast of northwest Africa, where the two continental margins curve away from each other rather than reaching toward one another as they do near the equator.
The difference between the narrowest and widest crossings is striking. You could fit the entire narrowest crossing inside the widest with well over a thousand miles to spare. This variation is not random. The Atlantic’s S-curve mirrors the shapes of the coastlines that border it. Where South America bulges east and Africa bulges west, the ocean pinches. Where North America and Africa angle apart, it balloons. The result is an ocean that, unlike the roughly circular Pacific, has a pronounced hourglass figure.
Why the Shape Looks the Way It Does
The Atlantic’s silhouette is a direct inheritance from the breakup of Pangea. When the supercontinent began rifting apart around 180 million years ago, the fracture did not follow a straight line.3Geology. Gibraltar subduction zone is invading the Atlantic It zigzagged along pre-existing weaknesses in the crust, and the resulting coastlines on either side of the new ocean preserved those irregularities. South America’s eastward bulge near Natal and West Africa’s corresponding indentation near the Gulf of Guinea are essentially matching halves of the same ancient rift.
As the continents drifted apart over millions of years, the Mid-Atlantic Ridge, the underwater mountain chain running roughly down the center of the ocean, continued pushing new seafloor outward in both directions. Because the ridge is not perfectly centered or perfectly straight, different sections of the ocean widened at slightly different rates and along slightly different angles. The net effect is that the Atlantic is widest where the continental margins have been diverging at the most open angle, and narrowest where they have stayed relatively close because of the geometry of the original breakup.
The Atlantic Is Still Getting Wider
The ocean is not a fixed basin. New crust forms continuously along the Mid-Atlantic Ridge and pushes the Americas and Europe-Africa apart at a rate of roughly one to two and a half centimeters per year, depending on the segment of the ridge. That is slow enough to be invisible in a human lifetime but adds up over geological time. A few centimeters per year translates to tens of kilometers per million years, and the Atlantic has been opening for 180 million of them.
This means the width measurements we use today are snapshots. The ocean you cross on a transatlantic flight is measurably wider than the one people crossed by steamship a century ago, though only by a meter or two. Over the next million years, the narrowest crossing between Brazil and Liberia will grow by roughly 15 to 25 kilometers, and the widest sections will widen proportionally.
But the Atlantic will not keep growing forever. Research modeling the behavior of the subduction zone beneath the Strait of Gibraltar suggests that this zone is slowly propagating into the Atlantic basin. In roughly 20 million years, the subduction zone’s slow phase is expected to end and it will begin invading the Atlantic at an accelerated rate, recycling oceanic crust on the eastern side.3Geology. Gibraltar subduction zone is invading the Atlantic This process could eventually lead to the formation of an “Atlantic ring of fire” analogous to the subduction zones ringing the Pacific, and it could mark the beginning of the Atlantic shrinking and eventually closing entirely as part of the Wilson Cycle, the grand process by which oceans are born from continental rifts, grow, and eventually shut down over hundreds of millions of years.
How Width Affects What Lives in the Water
The Atlantic’s width is not just a matter of geography trivia. It has real consequences for marine biology. Even at its narrowest, nearly 1,800 miles of open water is a formidable barrier for many species. Ocean currents do carry floating seeds, larvae, and drifting organisms between the coasts, but the distances involved mean that most of this transport is regional rather than transoceanic.
A study of the seagrass Halodule wrightii, which grows along coastlines on both sides of the tropical Atlantic, illustrates the point. Researchers found significant genetic differentiation between populations on the West Atlantic coast, in the Gulf of Mexico, and off West Africa. Biophysical modeling showed that ocean currents had a very low probability of moving genetic material between the eastern and western Atlantic coastlines, with most current-mediated gene flow occurring at regional scales of up to about 1,230 kilometers.4Scientific Reports. Long range gene flow beyond predictions from oceanographic transport in a tropical marine foundation species In other words, even in the narrowest part of the Atlantic, the gap is wide enough to effectively isolate populations on opposite shores and push them toward becoming genetically distinct over time.
This has broader implications beyond a single seagrass species. Many marine organisms that depend on currents for dispersal face the same barrier. The tropical Atlantic acts as a filter: strong swimmers and species with very long-lived larvae occasionally make the crossing, but most populations on the African and South American coasts evolve in relative isolation from each other. Interestingly, the study found some gene flow that exceeded what the ocean current models predicted, suggesting that rare long-distance dispersal events, possibly aided by storms, floating debris, or migratory animals, occasionally bridge the gap in ways that steady-state models do not capture.4Scientific Reports. Long range gene flow beyond predictions from oceanographic transport in a tropical marine foundation species
Comparing the Three Major Crossings
When people talk about the Atlantic’s width, they usually mean one of three crossings, each serving a different practical purpose and carrying a different distance:
- North Atlantic: Newfoundland to Ireland, about 2,060 miles (3,320 km). This is the classic transatlantic route for shipping and air travel between North America and Europe, and the path along which undersea telegraph cables were first laid in the nineteenth century.
- Tropical narrows: Cape São Roque, Brazil to Cape Palmas, Liberia, about 1,770 miles (2,850 km). The shortest open-water crossing, historically important for early aviation and for understanding the biogeographic split between South American and African species.
- Mid-Atlantic bulge: The widest section south of the North Atlantic route, exceeding 3,000 miles (4,800 km). Less commonly referenced in practical navigation because few major trade routes cross at this latitude, but it defines the ocean’s maximum breadth.
These three figures together give you the full range of the Atlantic’s width.1Encyclopædia Britannica. Atlantic Ocean The spread between the narrowest and widest is about 1,230 miles, a distance roughly equivalent to driving from New York to Miami.
Common Misconceptions About Atlantic Width
One frequent misunderstanding is that the shortest crossing between any two Atlantic-bordering countries must be the narrowest point of the ocean. It is not. The distance between, say, Canada and Greenland, or between Iceland and Scotland, is much shorter than the Brazil-to-Liberia crossing, but those are not true transatlantic measurements. They cross arms, straits, or marginal seas rather than the full open width of the main ocean basin. The narrowest point of the Atlantic proper refers to the shortest span across the open ocean where no intervening landmass breaks the crossing.
Another misconception is that the Atlantic is uniformly wide along most of its length and only narrows dramatically in one spot. In reality, the width changes continuously from north to south. The ocean narrows in the tropics, widens through the temperate latitudes, and narrows again in the far north as Europe and North America converge toward the Arctic. If you traced the width at every degree of latitude, you would get a wavy curve, not a flat line with one dip.
People also sometimes assume the Atlantic is the world’s widest ocean. It is not. The Pacific spans more than 12,000 miles at its widest near the equator, roughly four times the Atlantic’s maximum width. The Atlantic is the second-largest ocean by area, but it is a relatively narrow body of water compared to the Pacific’s vast expanse. Its length from north to south, on the other hand, is enormous, stretching from the Arctic to the Southern Ocean.
Undersea Cables and the Practical Cost of Width
The Atlantic’s width has direct economic consequences that most people never think about. Submarine fiber-optic cables connecting North America and Europe follow routes across the North Atlantic, roughly 3,000 to 4,000 miles long depending on the specific landing points and the cable’s path along the seafloor. Laying and maintaining these cables is one of the most expensive pieces of global telecommunications infrastructure, and the cost scales with distance. A cable crossing the narrow South Atlantic between Brazil and West Africa is significantly shorter, and newer cable routes are being planned and installed along this corridor to connect South America with Africa and onward to Asia, partly because the shorter crossing reduces both cost and signal latency.
Shipping follows a similar logic. The great circle route between New York and London covers about 3,450 miles, while the route between Recife, Brazil and Monrovia, Liberia is closer to 1,900 miles. Fuel costs, transit time, and exposure to mid-ocean weather all scale roughly with distance, so the narrower crossings offer practical advantages for certain trade flows. The tropical narrows have historically been less dominant in global shipping because the largest trade volumes flow between North America and Europe, but as economies in West Africa and South America grow, that narrowest crossing could become increasingly important for direct trade.
What the Width Means for Weather Patterns
The Atlantic’s width also shapes the weather on both sides. Tropical cyclones that form off the coast of West Africa have to cross the entire width of the ocean before reaching the Caribbean or the eastern United States. In the tropics, where the ocean is narrower, storms have less open water to traverse but still cover roughly 1,800 to 2,500 miles of ocean. That crossing time, typically five to ten days, is what gives forecasters their warning window. A wider Atlantic in the mid-latitudes would mean longer warning times for storms tracking at those latitudes, but most Atlantic hurricanes form and travel in the tropics and subtropics, where the crossing is shorter.
The ocean’s width also influences how much moisture air masses pick up before reaching land. Prevailing westerly winds crossing the wider sections of the North Atlantic absorb enormous quantities of moisture, dumping it as rainfall on Western Europe. The relatively narrower tropical section means that air crossing from Africa to South America carries less moisture picked up over water, though the warm sea surface temperatures in the tropics compensate somewhat by driving more intense evaporation per mile of ocean surface. The interplay between width, temperature, and wind direction creates distinct precipitation patterns on each side of the ocean at each latitude, a reminder that the shape of an ocean basin is not just a measurement but a driver of the climate systems millions of people live under.