The Atlantic Ocean Lesson: Depths, Size & Shape

Lesson Overview

• Size and Global Rank of the Atlantic Ocean
• Proportion of Earth's Surface Covered
• Depth of the Atlantic: Average Depth and Unit Conversion
• The Atlantic's Deepest Point
• Shape of the Atlantic Basin
• Connections to Other Oceans and Seas
• Historical Mentions and Significance of the Name "Atlantic"

The Atlantic Ocean is one of Earth's five major oceans and a vital part of our planet's geography. It stretches between the continents of North and South America on one side and Europe and Africa on the other. 

For centuries, the Atlantic has been a highway for exploration, trade, and cultural exchange. This lesson will guide you through key facts about the Atlantic Ocean, from its size and depth to its unique shape and historical significance. 

Size and Global Rank of the Atlantic Ocean

One of the first things to know is how big the Atlantic Ocean is compared to other oceans. On a global scale of ocean sizes, the Atlantic ranks second. Only the Pacific Ocean is larger. To put this in perspective, here's a comparison of the five oceans by area:

From the table, you can see the Atlantic Ocean is indeed the second-largest ocean on Earth. It covers an enormous area of roughly 106 million square kilometers.

Proportion of Earth's Surface Covered

Just how much of our planet's surface is the Atlantic Ocean? The Atlantic covers about 20% of Earth's surface area. In other words, one-fifth of the entire globe (land and water combined) is the Atlantic Ocean! This is a huge portion of Earth. Another way to think of it is that the Atlantic makes up nearly one-third of the world's ocean surface (since oceans cover about 71% of Earth).

This high percentage emphasizes the Atlantic's importance in global systems. For instance, the vast surface area means the Atlantic plays a major role in climate regulation (through heat transport in water) and supports diverse marine habitats. It also explains why the Atlantic has been so crucial for human navigation - you simply can't avoid it when traveling between the eastern and western hemispheres.

Geographic Location and Coordinates

The Atlantic Ocean's location spans a wide range of latitudes and longitudes. It reaches from the northern polar regions all the way down to near Antarctica in the south. It also stretches wide from east to west, filling the space between the Americas and Africa/Europe. One way geographers pinpoint locations in the Atlantic (or anywhere on Earth) is by using coordinates (latitude and longitude).

More generally, the Atlantic Ocean covers a huge band of coordinates:

• Latitude span: from about 70°N (in the far North Atlantic, touching the Arctic Circle) down to about 60°S (where the South Atlantic meets the icy Southern Ocean near Antarctica).
  
• Longitude span: from near 80°W (western Atlantic, e.g. near the Americas) to about 20°E (eastern Atlantic, near Africa's southern tip).

Because the Atlantic crosses the Equator, it is naturally divided into the North Atlantic and South Atlantic. Many maps mark the Atlantic's expanse with such coordinates, helping navigators and learners alike to understand its position on the globe.

Depth of the Atlantic: Average Depth and Unit Conversion

When we talk about ocean depth, we often want to know both the average depth and the deepest points. The Atlantic Ocean has an average depth of about 11,962 feet. This figure means that if you could magically level the entire Atlantic basin, the water column would be around 11,962 feet deep everywhere. 

In reality, of course, some areas are much shallower (like continental shelves near coasts) and some are much deeper (like ocean trenches). That average is a result of measuring depths all over the ocean and finding the mean value.

To better understand that number, it helps to convert it into more familiar units. Scientific work typically uses meters. Let's convert 11,962 feet to meters step by step:

1. Know the conversion factor: 1 foot equals 0.3048 meters (since a meter is about 3.281 feet).
2. Multiply the depth in feet by this factor: 11,962 feet × 0.3048 (m/ft).
3. Calculate the result: 11,962 × 0.3048 ≈ 3,646 meters.

So, the average depth of the Atlantic Ocean is roughly 3,646 m (which is about 3.65 kilometers). We can round it as ~3.6 km for simplicity.

Now, what does an average depth of 3.6 km mean in a real-world sense? It's very deep. For comparison, the tallest mountains on land (like the Himalayas) are around 8–9 km high. So an average depth of 3.6 km means much of the Atlantic seafloor is like valleys deeper than many mountains are tall. Measuring this depth is complex: oceanographers use echo-sounding from ships and satellite data to map the seafloor and gather these figures.

The Atlantic's Deepest Point

While the average depth gives a general idea, you might be wondering: how deep does the Atlantic Ocean get at its deepest? The answer is astounding. The Atlantic's deepest known point is about 27,841 feet below the surface. 

This deepest spot is located in the Puerto Rico Trench, specifically a part of it often called the Milwaukee Deep, just north of the island of Puerto Rico in the Caribbean region. At nearly 8.5 km deep, this trench is an almost unfathomable abyss.

To help visualize this depth, compare it to Mount Everest, the tallest mountain on land:

• Mount Everest's height is about 8,848 m (29,029 ft).
• The Puerto Rico Trench is ~8,486 m deep (27,841 ft).

If Mount Everest were placed in the deepest part of the Atlantic, its peak would almost reach the ocean surface, but not quite - it would still be a few hundred meters underwater! That comparison shows just how deep the ocean floor goes in the Atlantic's extreme points.

Understanding the deepest point also highlights the conditions there: it's completely dark, the pressure is immense, and very few life forms can survive such depths. Yet, specialized sea creatures and microbial life have been found even in these trenches, which fascinates scientists.

Shape of the Atlantic Basin

If you look at a world map or globe, you might notice the Atlantic Ocean has a distinctive "S" shape in its north-south orientation. Let's explore why the Atlantic is described this way.

Imagine tracing the Atlantic Ocean's outline from the north down to the south:

• In the North Atlantic, near the top of the "S", the ocean lies mainly between North America (on the west) and Europe (on the east).
  
• Moving southward, the ocean narrows around the Equator region, somewhat like the middle bend of an "S". Here, South America and Africa face each other more closely.
  
• Further down in the South Atlantic, it broadens again between South America (west) and Africa (east), curving the opposite way, like the bottom of an "S", until it opens out toward Antarctica.

This alternating widening and narrowing gives an overall impression of an elongated S curve. The Atlantic's basin (the depression in Earth's crust that holds the ocean) was shaped largely by plate tectonics. 

Over 100 million years ago, the single supercontinent Pangaea split apart, and the Americas drifted away from Europe and Africa. The path of this separation, combined with the outline of the continents' coasts, resulted in the sinuous outline of the Atlantic we see today.

Several factors contribute to the Atlantic's shape:

• Continental arrangement: The way continents are distributed (with the Americas on one side and Europe/Africa on the other) essentially frames the Atlantic's boundaries.
  
• Mid-Atlantic Ridge: This massive underwater mountain range runs down the middle of the Atlantic. It creates a kind of central spine. While mostly under the surface, it influences the topography and basin shape.
  
• Coastal features: The Atlantic has many bays, gulfs, and seas (like the Gulf of Mexico, the Mediterranean Sea, the Bay of Biscay, etc.) which indent the coasts. These features add to the jagged, curved edges of the ocean's outline.
  
• Earth's curvature and map projection: How we look at a flat map can exaggerate certain shapes. However, even on a globe, the S-like alignment is evident due to how the northern and southern parts of the ocean offset from each other.

Try locating the Atlantic on a map and tracing its shape with your finger - you'll notice the "S" curve path it takes. This shape isn't just a trivial fact; it affects ocean currents and climate patterns. For example, the narrowing at the equator contributes to powerful currents like the Gulf Stream in the north and the Brazil Current in the south.

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Connections to Other Oceans and Seas

The world's oceans are all connected as one global body of water. The Atlantic Ocean, in particular, has direct connections to several other oceans. 

• North – Arctic Ocean: In the far north, the Atlantic Ocean blends into the Arctic Ocean. If you travel northward through the North Atlantic (past Iceland and Greenland), you eventually enter the Arctic Ocean. On a compass, going north from the Atlantic leads you to the Arctic. The boundary is not a sharp line but a gradual transition in the waters around Greenland and the Norwegian Sea.
  
• Southwest – Pacific Ocean: The Atlantic connects with the Pacific at the southwestern extreme of the Atlantic. How? If you go to the tip of South America (Cape Horn) and head westward, the Atlantic waters meet the Pacific in a passage known as the Drake Passage. This is essentially a southwest direction from much of the Atlantic. Another way the Atlantic and Pacific are connected is artificially through the Panama Canal (near the Equator), but naturally, the Drake Passage is where the two great oceans mingle.
  
• Southeast – Indian Ocean: If you head southeast from the South Atlantic, you round the Cape of Good Hope at the southern tip of Africa. There, Atlantic waters meet the Indian Ocean. The connection is roughly toward the southeast on a compass. In fact, the official dividing line between the South Atlantic and Indian Ocean is often set at a certain line of longitude near that area.
  
• South – Southern Ocean: As you go farther south, the Atlantic opens into what we call the Southern Ocean (the ocean encircling Antarctica). Essentially, at the very southern reaches of the Atlantic, it transitions into the cold Southern Ocean. This is directly south on the globe.

In summary, the Atlantic Ocean is connected to all other major oceans:

• To the Arctic Ocean in the north,
• To the Pacific Ocean in the southwest,
• To the Indian Ocean in the southeast,
• And to the Southern Ocean in the far south.

These connections mean that water (and ships, and marine life) can ultimately travel between the Atlantic and other oceans. For example, the Gulf Stream current in the Atlantic eventually feeds into currents that reach other oceans. Historically, these connections also mattered for navigation; explorers had to find routes from the Atlantic to the Pacific (like Magellan did, going southwest around South America).

Historical Mentions and Significance of the Name "Atlantic"

The Atlantic Ocean is not just important in physical terms; it also has a rich historical and cultural significance. Some of the earliest known references to the Atlantic Ocean (by name) date back to around the 6th century BCE (Before Common Era) in ancient Greek sources.

The name "Atlantic" itself comes from Greek mythology. It is derived from "Atlantis" or "Atlas." Atlas was a Titan in mythology who was said to hold up the sky. The Greeks named the ocean beyond the Pillars of Hercules (the Strait of Gibraltar) the "Sea of Atlas" (Atlanticus Pelagus). Herodotus, a Greek historian of the 5th century BCE, mentioned the Atlantic in his writings, and we believe even earlier, a Greek poet in the 6th century BCE spoke of the Atlantic as the 

Some other historical nuggets about the Atlantic:

• The ocean was sometimes referred to as the "Western Ocean" by medieval Europeans, because it lay to the west of Europe.
• It was also dubbed the "Sea of Darkness" by some earlier civilizations who found it frightening to venture into, before the age of exploration.
• With the Age of Exploration (15th–16th centuries CE), the Atlantic became the stage for famous voyages by Columbus, Vasco da Gama, and others, connecting the Old World and New World.