What are the 5 Oceans of the World?

January 11, 2024

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Map showing the 5 oceans of the world

If you look at the Earth from space, you’ll see that we live on a blue planet. Over 70% of the world is covered by oceans and seas. Technically there is only one global ocean but we have geographically defined ocean basins that are divided by the planet’s continents. Other factors, such as temperature and flow of currents, also help to differentiate one ocean from another.

Historically, it was acknowledged that the the world had four oceans: the Pacific, Atlantic, Indian, and Arctic. Although bodies such as the National Oceanic and Atmospheric Association have for decades recognized the Southern Ocean as a fifth ocean, it is has never been officially recognized by the International Hydrographic Organization.

However, opinion has changed dramatically in the last few years since the National Geographic Society announced on World Oceans day 2021 that it would recognize the Southern Ocean on its maps.

With that in mind, let’s take a look at the oceans of the world, ranked by size.

1. The Pacific Ocean

A humpback whale rising up out of the water in the Pacific Ocean. Land is just visible along the top of the image.
Humpback whale breaching the water in the Pacific Ocean
Area: 155,557,000 km² (60,060,893 sq mi)
Average depth: 4,280 m (14,040 ft)
Max. depth: 10,911 m (35,797 ft)

The Pacific Ocean is the world’s largest ocean, with a total area of 155,557,000 km² (60,060,893 square miles). It covers 30% of the Earth’s surface, which is larger than the combined surface area of land on Earth (which covers 29%).

The Pacific Ocean is also the deepest body of water on our planet. It’s home to the deepest point on Earth, the Challenger Deep in the Mariana Trench, which has a depth of almost 11,000 meters (35,797 feet).

Asia and Australia are separated from the Americas by the Pacific Ocean. The ocean stretches from the Antarctic region in the South to the Arctic in the North. The next largest ocean, the Atlantic Ocean, is half the size of the Pacific.

Ferdinand Magellan, a Portuguese explorer, named the ocean in 1520. He called it ‘pacific’, (or Mar Pacífico), meaning ‘peaceful’ in Portuguese, inspired by the water’s calmness.

Due to its colossal size, thousands of different species call the Pacific Ocean home. Many species are endemic, meaning they are only found here. The Pacific is home to several penguin species, such as the Magellanic Penguin and the Rockhopper Penguin. Humpback and Killer whales also live in these waters, as do manta rays, sea turtles, and giant squids.

Over 40 sovereign countries and over 20 territories border the Pacific Ocean. As most parts of the ocean have a low latitude, the Pacific’s climate is largely tropical and subtropical. Despite its calm name, the Pacific is also prone to tropical cyclones, which can cause significant damage if strong enough.

The waters near the equator are calmer and have low salinity. This is because there is high rainfall near the equator and little evaporation.

2. The Atlantic Ocean

Sun setting over the open water of the Atlantic Ocean. The sky is transitioning from blue to pink and gold. The clouds are cast in a dark grey light.
Sun setting over the Atlantic Ocean
Area: 76,762,000 km² (29,637,974 sq mi)
Average depth: 3,646 m (11,962 ft)
Max. depth: 8,376 m (27,480 ft)

This saltwater ocean is the world’s second-largest body of water. Its name originates from Greek mythology and means ‘sea of Atlas’. A Greek historian called Herodotus made the earliest known reference to this name in 450 B.C.

The Atlantic Ocean separates the ‘Old World’ of Africa and Europe from the ‘New World’ of the Americas. It has a loose ‘S’ shape and is long and narrow. The ocean is connected to the Arctic Ocean in the north, the Southern Ocean in the south, the Pacific Ocean in the southwest, and the Indian Ocean in the southeast.

The Atlantic Ocean borders over 100 countries and territories from five different continents. It covers approximately 20% of the Earth’s surface. Scientists often divide the ocean into two parts: the North Atlantic and the South Atlantic. Water in the North Atlantic sinks after being chilled by low temperatures in the Arctic, which starts the global ocean conveyor. This is a global circulation pattern that helps regulate the planet’s climate.

Various endangered animals live in the Atlantic Ocean, such as Sperm Whales, Hooded Seals, and Great White Sharks. The Atlantic Ocean also has various coral reefs, especially in the Caribbean, although these are less diverse than those in the Pacific.

The Atlantic Ocean typically has a mild climate. Fog is often a problem for ships sailing the Atlantic as the warm water mixes with the cold air. Tropical storms form hurricanes and cyclones near the equator, which can cause severe damage on the coasts if they blow inland.

Many animals in the Atlantic Ocean migrate to colder regions. Whales, for example, are prone to migrating from the Atlantic to Greenland and Iceland once food supplies have grown scarce after the summer. While this is a natural process, global warming has increased the number of fish migrating to cooler waters.

3. The Indian Ocean

Picture of a tree-lined island overlooking the blue water of the Indian Ocean on a sunny day Description: picture of an island on a sunny day. The island is covered in vegetation and is overlooking the dark turquoise water of the Indian Ocean.
Edge of an island overlooking the Indian Ocean
Area: 68,556,000 km² (26,469,620 sq mi)
Average depth: 3,741 m (12,274 ft)
Max. depth: 7,258 m (23,812 ft)

Nearly 40 countries and territories in four different continents border the Indian Ocean. It lies between Asia to the north, Africa to the west, Australia to the east, and the Southern Ocean to the south.

The body of water covers approximately 20% of the Earth’s surface. The deepest part of the Indian Ocean is in the Java Trench, which is estimated to be 7,450 meters (24,442 feet) deep.

This ocean was known as the Eastern Ocean before approximately 1515 when it was renamed Oceanus Orientalis Indicus (meaning ‘Indian Eastern Ocean’). Conversely, the Atlantic was known as the ‘Western Ocean’.

The Indian Ocean is Earth’s warmest ocean basin; the water becomes warmer nearer the equator. Temperatures vary depending on the ocean currents and location. Coastal areas near the equator even have temperatures of around 28°C (82°F).

Around 30% of the world’s reef cover is found in the Indian Ocean. Not only do coral reefs provide a habitat for different marine species, but they also prove a vital part of the tourist industry for nearby coastal regions.

Endangered fish species such as the Angelfish and Butterflyfish are found around The Seychelles (115 islands off the coast of East Africa). Octopus and spiny lobster are also found in this region. Five out of the world’s seven turtle species are found in the Maldives (South Asia).

4. The Southern Ocean

Picture of several iceblocks on the surface of the gray Southern Ocean
Ice blocks on the Southern Ocean
Area: 20,327,000 km² (7,848,299 sq mi)
Average depth: 3,270 m (10,728 ft)
Max. depth: 7,236 m (23,740 ft)

The Southern Ocean circles Antarctica and is the only ocean that is uninterrupted by land. It was formed approximately 34 million years ago, which makes it the world’s youngest ocean basin. It covers somewhere between 10 to 15% of the Earth’s surface.

This ocean is home to a fantastic array of marine life; killer whales, Sleeper sharks, and Adelie penguins are all found in these waters. Elephant seals, the largest seal species, also live in the Southern Ocean, as do Emperor penguins, the largest penguin species.

There are few fish species in different families in the ocean. Most fish species fall into the snailfish, cod icefish, and eelpout families. Multiple species have also been identified but not formally named and described.

During winter months, the Southern Ocean freezes into a fringe of sea ice. This causes Antarctica to almost double in size. The ice melts away in the warmer summer months. The ocean’s temperature ranges anywhere from 2°C (28°F) to 10°C (50°F).

5. The Arctic Ocean

Icebergs in the dark blue Arctic Ocean
Icebergs in the Arctic Ocean
Area: 14,056,000 km² (5,427,052 sq mi)
Average depth: 1,038 m (3,406 ft)
Max. depth: 5,502 m (18,050 ft)

The smallest of Earth’s oceans, the Arctic Ocean, is by no means less impressive. It covers an area of 14,056,000 km² (5,427,052 sq. mi), which is about 1.5 times the size of the United States. The Arctic Circle covers approximately 4% of the Earth’s surface. Russia, Norway, Iceland, Greenland, Canada, and Alaska border the Arctic Ocean.

During winter, the ocean’s temperature can drop to a numbing -30°C (-22°F) and around 0°C (32°F) in the summer. These cold temperatures are the perfect environment for animals with thick blubber that maintains their body temperature. Species such as beluga whales, walruses, and narwhals live in the Arctic Ocean, as do an estimated 240 fish species. This includes families such as sculpins, snailfish, and eelpouts.

Due to the cold temperature of the water, the Arctic Ocean features glacier ice. Glaciers store an estimated 75% of the Earth’s freshwater supply. Alaska, which borders the Arctic Ocean, is estimated to have around 100,000 glaciers alone. However, like with the rest of the globe, the Arctic is warming, and much of the ice is melting.

Since 1979, the Arctic has warmed nearly four times faster than the rest of the world. Many animals rely on the glacier ice in the Arctic Ocean for feeding or resting. The lack of ice is disrupting the Arctic food chain, and many species are migrating to regions outside their natural feeding grounds.

The name ‘arctic’ comes from the Greek words ‘arktikos’, meaning ‘near the bear’ or ‘northern’, and arktos, which means ‘bear’. However, the ancient Greeks weren’t naming the region after polar bears! Instead, the name refers to the Ursa Major constellation, otherwise known as the Great Bear. This constellation is seen in the northern sky and can be seen throughout the year in the Northern Hemisphere.

FAQs

Overview: Oceans of the World

Of the planet’s five oceans, the Pacific is the largest and the Arctic is the smallest. The Pacific Ocean is also the world’s deepest ocean, with a maximum depth of 10,911 meters (35,797 feet). The Indian Ocean is the warmest ocean in the world and the Arctic is the coldest.

Although most species live on land, the oceans are important to the world’s food chains. Global warming is significantly impacting the oceans, particularly the Arctic Ocean. Conservation efforts is one of the major reasons the Southern Ocean was officially named the fifth ocean, so scientists could study this specific region.

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