Our blue planet is incredible. Stretching far and wide, huge bodies of saline water hug land masses and dominate the surface. Together, they cover around three quarters of the entire Earth’s surface, and sink deep into a vastly unexplored abyss. Still much remains unknown, although much has been discovered, in our oceans. Through geo-mapping and political arrangement, there are officially five – each with their own biodiversity, topography and quirks. We break it all down for you:

Pacific Ocean

The Pacific Ocean is the largest ocean, around 15 times the size of the United States. With 25,000 islands in the region, the ocean also contains the most biodiverse waters in the world – thanks to the Coral Triangle. Even though the Pacific Ocean is best known for its incredible fauna, it also contains an incredible array of plants and coral reefs.

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Size: 165.25 million square kilometres

Average depth: 4,280 metres

Deepest Point: Mariana Trench, 10,911 metres

Surface temperature: From -1.4ºC in poleward areas to 30ºC near to the equator

Covers: 30.5% of Earth’s total surface area

Boundaries: Asia, Australia, the Americas

Notable dive locations: Great Barrier Reef, Lembeh Strait, Komodo, Sipadan, Palau, Malapascua, Tubbataha, Chuuk Lagoon, Raja Ampat

Interesting facts:

  • 60% of the world’s fish come from The Pacific Ocean
  • The Pacific Ocean shrinks in size by just over two centimetres each year
  • The Pacific Ocean Basin is home to 75% of the world’s volcanoes
  • There are more than 25,000 islands in the Pacific
  • Pacific Ocean was declared “Mar Pacifico” in 1521 which is Portuguese for “Peaceful Sea”

Atlantic Ocean

Containing most of our planet’s shallow seas – but with relatively few islands – the Atlantic Ocean is a relatively narrow body of water that snakes between nearly parallel continental masses, the Americas, Europe and Africa. Famed for offering incredible encounters with large pelagics in the Caribbean, Mediterranean, Baltic, and the Gulf of Mexico. The Mid-Atlantic Ridge, that runs roughly down the centre of the ocean, separates the Atlantic Ocean into two large basins.

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Size: 82.36 million square kilometres

Average depth: 3,339 metres

Deepest Point: Puerto Rico Trench, 8,605 metres

Surface temperature: From -2 ºC in the polar regions to over 30 ºC north of the equator

Covers: 20.8% of Earth’s total surface area

Boundaries: The Americas, Europe, Africa and Antarctica

Notable dive locations: Grand Bahama, Cozumel, Grand Cayman, British Virgin Islands, Bermuda, Bonaire, The Great Blue Hole, Honduras

Interesting facts:

  • The name Atlantic comes from the Greek word Atlantikos which was known in the English language at the time, as the Sea of Atlas
  • The Atlantic Ocean is the world’s saltiest sea with a water salinity level of between 33 – 37 parts per thousand
  • It’s the world’s youngest ocean, formed long after the Pacific, Indian and Arctic Oceans of the Triassic Period
  • Home to the earth’s largest mountain range, The Mid Atlantic Ridge, which is 40,000 kilometres long by 1,601 kilometres wide – dividing the ocean into two distinct east and west regions
  • The Atlantic is famous for being the home of the legendary area known as the Bermuda Triangle, an area renowned for the mysterious disappearance of several aircraft and ships

Indian Ocean

The Indian Ocean is enclosed on three sides by landmasses of Africa, Asia, and Australia. The southern border is wide open and exchanges with the much colder Southern Ocean. With relatively few islands, the continental shelf areas tend to be quite narrow and not many shallow seas exist. Some of the major rivers flowing into the Indian Ocean include the Zambezi, Indus, and the Ganges. Because much of the Indian Ocean lies within the tropics, this basin has the warmest surface ocean temperature.

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Size: 73.56 million square kilometres

Average depth: 3,960 metres

Deepest Point: Sunda Deep, 7,450 metres

Surface temperature: N/A

Covers: 14.4% of Earth’s total surface area

Boundaries: Africa, Asia, Australia/Oceania

Notable dive locations: Seychelles, Oman, Maldives, Musandam, Bali

Interesting facts:

  • The ocean is the warmest ocean in the world and offers little scope to plankton and other species for growth
  • It is estimated that approximately 40% of the world’s oil comes from the Indian Ocean
  • There was a discovery of a submerged continent in the Indian Ocean named the Kerguelen Plateau, it is believed to be of volcanic origins
  • The Ocean’s water evaporates at an abnormally high rate due to its temperature
  • Every year it is estimated that the Indian Ocean becomes approximately 20 centimetres wider

Southern Ocean

Compared to the other five oceans, the floor of the Southern Ocean is quite deep – ranging from 4,000 to 5,000 metres below sea level over most of the area that it occupies. In September of each year, a mobile icepack situated around the Antarctic reaches its greatest seasonal extent covering around 19 million square kilometres– later in March the icepack shrinks by almost 85%.

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Size: 20.3 million square kilometres

Average depth: 4,496 metres

Deepest Point: South Sandwich Trench, 7,235 metres

Surface temperature: -2 to 10 ºC

Covers: 4.0% Earth’s total surface area

Boundaries: Antarctica

Notable dive locations: Polar diving in Antarctica

Interesting facts:

  • The world’s largest penguin species, the emperor penguin, lives on the ice of the Southern Ocean and on the Antarctica continent. Along with the world’s largest animal, the blue whale, who often calls these waters home
  • Antarctica is home to 90% of the world’s ice. This continent contained within the Southern Ocean’s boundaries is the windiest, driest and coldest continent in the world
  • Having been only officially recognised in 2000, there is still some controversy as to whether it should be considered a separate ocean or merely an extension of the Atlantic, Pacific and Indian Oceans
  • The ocean is the youngest of the five oceans at only 30 million years of age and formed when the continents of South America and Antarctica completely split apart
  • Clouds are brighter in the Southern Ocean due to large plankton blooms, which release gases that allow water droplets to spread out more thus creating more reflective clouds

Arctic Ocean

The world’s smallest and shallowest (on average) ocean is also one of its most interesting. The crown of the world, both above and below the waves, enchanting creatures from narwh
als to belugas sound out in the deep depths.

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Size: 14.05 million square kilometres

Average depth: 1,050 metres

Deepest Point: Litke Deep in the Eurasian Basin, 5,450 metres

Surface temperature: Average -1.8 ºC

Covers: 2.8% of Earth’s total surface area

Boundaries: Europe, Asia, North America

Notable dive locations: Greenland, Baffin Island

Interesting facts:

  • There are four whale species in the Arctic Ocean including the bowhead whale, grey whale, narwhal, and beluga whale
  • When the ice of the Arctic Ocean melts it releases nutrients and organisms into the water which promotes the growth of algae. The algae feed zooplankton which serves as food for the sea life
  • Because of the Arctic Ocean’s low evaporation, large freshwater inflow, and its limited connection to other oceans it has the lowest salinity of all oceans. Its salinity varies depending on the ice covers’ freezing and melting
  • Icebergs often form or break away from glaciers posing a threat to ships the most famous being the Titanic. Ships also often get trapped or crushed by the ice
  • Ice cover of the ocean is shrinking due to global warming, and it has been observed that the rate of disappearance of ice cover is 3% per decade