Oceans of the World

We might call it planet earth, but it’s really the oceans that dominate our world. Together they cover a massive 71% of the surface, making this a particularly wet place to live. It’s probable that life here began in vast ancient seas, and even now we still rely on them. We use oceans to transport people and goods between continents, but also to supply food, employment, and fun. Beautiful and sometimes terrifying, our stunning oceans remain a constant source of mystery and fascination.

The world has numerous seas, but only five oceans. The largest is the Pacific Ocean, then the Atlantic Ocean, the Indian Ocean, the Southern Ocean and the freezing Arctic Ocean.

Hawksbill Turtle swims under water and passing coral reef.

The Pacific Ocean

An immense body of water that covers more than 33% of the planet’s surface, the Pacific is undoubtedly our largest ocean. Half of all the liquid water we have sits here, between three giant continents, Australasia, Asia and The Americas. Within its southern Arctic boundaries, you can find icy cold regions, whilst further toward the equator, temperatures rise considerably. The deepest spot in the seabed is found here in the Mariana Trench. Known as Challenger Deep, it has been mapped by submersibles and is around 10 900 metres deep.

Idyllic islands, like Hawaii, Fiji and Tahiti are found here, alongside more remote and mysterious places like Easter Island. In all up to 30 000 different islands are located in the Pacific, and as you move from north to south, the wildlife, culture, and geographical features change radically.

The Pacific is a key shipping route, with nearly half of all ocean-borne freight crossing over in giant containers. Sharing the space are marine animals like sea lions, whales and Loggerhead Turtles, which move back and forth between Japan and the US, to lay their eggs and find food.

Atlantic Ocean

Covering about 20% of the planet’s surface, the Atlantic Ocean sits between Europe, the Americas, and Africa. In the areas where it meets the Arctic the waters are extremely cold, but further towards the south and nearer the equator, warmer currents are the norm. It is so deep that a range of mountains is partially hidden beneath its surface. The Mid-Atlantic Ridge systems are central to the Atlantic, forming a geological colossus that is larger than any other natural structure in the sea, or on land. This World Heritage Site includes volcanic islands like Iceland and the Ascension Island, that lies between Brazil and Africa.

The Gulf Stream which flows as a warm powerful current from the Gulf of Mexico, is another major feature of this ocean. It can keep even the most northerly Atlantic ports free from ice, by delivering a taste of toasty tropical heat. Sharks, whales and giant octopi have all made these waters their home, but overfishing for cod and tuna is a major issue which has a knock-on effect on larger creatures.

Map of the Gulf and North Atlantic Stream in the Atlantic Ocean. Red arrows used in illustration.

Indian Ocean

The exquisite Indian Ocean is the third largest in the world, and also the warmest. It is nestled between the balmy shores of Africa and Australia, to the south of Asia. The Java Trench is the deepest area, where depths of over 7000 metres have been recorded. This expanse is home to many gorgeous archipelagos, small chains of islands like the Maldives and the Seychelles that are made of coral. Most of the islands are now home to tourist centres or used for agriculture, just 185 of the 1190 tiny islands which make up the Maldives are home to indigenous communities. The waters are considered to be tropical, offering a warmth that is ideal for many species of shark and some highly toxic jellyfish, like the mauve stinger.

The Indian Ocean is popular with holidaymakers in part because of its crystalline shallows. This flawless appearance is another result of warmth, as the deeper colder layers are more attractive to plankton, so they keep away from the shore.

Each year the currents in this area change direction twice, meaning the water actually begins to flow the opposite way. We cannot observe this phenomenon anywhere else on earth, but it is a result of humid monsoon winds sweeping over the ocean.

Southern Ocean

Located at the edges of Antarctica and the South Pole, the Southern Ocean is the fourth largest and the only body of water which encircles the world. It is so vast and cold that many sections freeze in the winter months, creating massive icy sheets. High winds and towering waves make the waters even more inhospitable, to humans at least.

For animals and fish, this is a rich feeding ground packed with nutrients that support huge quantities of plankton. These microscopic organisms are the bottom of a food chain that includes fish, mammals and eventually birds.

Along with penguins, petrels and gulls, our largest seabird lives here. The wandering albatross has an impressive wingspan of 3,5m and it lives mainly out to sea. They return to breed on land once every two years, usually with the same partner.

Arctic Ocean

Smaller and shallower, the Arctic Ocean surrounds the North Pole but reaches down to Scandinavia, Asia and North America. Due to its extremely remote and icy location, much of the Arctic freezes over during six months each year, between December and May. This is when predatory polar bears begin stalking the ice packs, searching for seals. Other visitors include grey whales, humpbacks and bowheads, which make the most of the summer months here, feeding on copious amounts of oily fish.

Because of climate change, temperatures in the oceans have risen and the polar ice which surrounds the Arctic is melting at an accelerated rate. According to the World Wildlife Fund this part of the world is worse affected by global warming, because the shiny ice patches which reflect heat energy back into the atmosphere are gradually disappearing.


Oceans are Integral to Life on Earth
These enigmatic expanses influence our weather systems and climate, transporting rain clouds and warm waters over the equator to the poles, then back once more to tropical climes. This type of regulation evens out the distribution of energy from the sun, and the oceans also act like a giant solar panel, enabling the earth to absorb and retain heat. Without our oceans, super-cold and super-hot areas would quickly develop, making large regions of the earth uninhabitable.

Wild and Unexplored
Although oceans cover most of the earth and half of all terrestrial species live there, we have yet to explore around 95% of our seas. Scientists used to believe that biodiversity was reduced at greater depths, but now they think that isn’t the case. We can’t record every species in the deep ocean because such complex and expensive equipment is needed. Although twelve people have walked on the moon, incredibly, no human has yet visited the deepest undersea regions of the earth.

What is World Oceans Day?
Taking place on June 8th each year, World Oceans Day is a global event that was launched in 1992, by the International Centre for Ocean Development in Canada. In 2008, the UN began to back World Oceans Day, offering the event more publicity than ever before, and encouraging people from a wider range of countries to take part. Since then it has constantly grown in size, with the 2017 celebrations boasting 1000 different events in 100 different countries.

Anyone can be part of the day, so if you want to get involved with protecting our seas in a practical way, World Oceans Day has resources and guidance to help you raise funds and awareness in your local community. From art exhibitions to fairs, races to clean-ups, family, friends, and neighbours, can all come together to join in with activities that promote clean and healthy oceans.

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These information were not written by the American Food and Drug Administration, or any other official authority. This site and its products do not promise to diagnose and cure diseases, or protect you from them. Always consult your doctor when you are sick.