All You Need To Know About the World’s 5 Oceans
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.
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.
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.
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%.
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.
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