Blog about Underwater Life and Scuba Diving

A Guide To The Ocean

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Know Your Ocean!

I love to read facts about things, especially when it turns out that something that you take for granted is actually an astonishing force of nature. We all like the sea; some of us only like to watch it from the comfort of a cafe window or park bench, some of us like to sail it and others like to get into it and explore as much of it as we can!

The Ocean Is An Awesome Force, And The More I Learn About It The More I Want To Dive It!

There are many reasons that divers love the seas, but none can be as compelling as the fact that we know very little about this vast expanse of our world. We have explored little of it and have fully examined a tiny fraction of its area. The ocean is impressive in many different ways, yet we know very little about it. This makes me even more keen to strap a tank on my back and go find out for myself!

What I’ve done here today is complied a list of amazing, impressive, humbling and depressing facts to inspire your sense of wonder, and to widen your eyes to its delicate balance that we are upsetting. I’m no eco-warrior, but the facts below make even me think twice before I buy fish without researching its origin. You might already know a few of these facts, but I’m sure there will be a couple of gems in there that you can whip out at the pub or on the dive boat to impress your friends!

The Physical Ocean

Earth has five major oceans. The largest is The Pacific, located between the Southern Ocean, Asia, Australia and the western hemisphere, over an area about 15 times the size of the USA. It contains more than 25,000 islands.

The Challenger Deep is the lowest spot in all the world’s oceans, located in The Pacific. To put its depth into perspective, if you dropped in Mount Everest (8,850 metres high), there’d still be more than a mile of ocean above it!

The Submarine Trieste Was The First Sub To Venture To The Deepest Point On Earth.

The Dead Sea is the Earth’s lowest land point with an elevation of 396m below sea level.

Australia’s Great Barrier Reef covers an area bigger than Great Britain and can even be seen from space. The Reef is a collection of islands which are home to over 400 types of coral and among which live more than 2,000 species of fish.

The Barrier Reef Is True Wonder Of The World, It Can Be Seen From The Moon!

The Earth’s longest mountain range is underwater. The Mid-Ocean Ridge runs around the globe from the Arctic to the Atlantic, via Africa, Asia and Australia. That’s four times longer than the Andes, Rockies and the Himalayas combined.

The oceans occupy nearly 71% of our planet’s surface

More than 97% of all our planet’s water is contained in the ocean

The top ten feet of the ocean hold as much heat as our entire atmosphere

The average depth of the ocean is more than 2.5 miles

The sea level has risen with an average of 10-25 cm over the past 100 years and scientists expect this rate to increase. Sea levels will continue rising even if the climate has stabilised, because the ocean reacts slowly to changes. 10,000 years ago the ocean level was about 110 m lower than it is now. If all the world’s ice melted, the oceans would rise 66 m.

The average temperature of all ocean water is about 3.5°C.

Antarctica has as much ice as the Atlantic Ocean has water.

The oceans provide 99 percent of the Earth’s living space – the largest space in our universe known to be inhabited by living organisms

More than 90% of this habitat exists in the deep sea known as the abyss

Less than 10% of this living space has been explored by humans

The Monterey Bay Submarine Canyon is deeper and larger in volume than the Grand Canyon

The Antarctic ice sheet that forms and melts over the ocean each year is nearly twice the size of the United States

The average temperature of the oceans is 2ºC, about 39ºF

Water pressure at the deepest point in the ocean is more than 8 tons per square inch, the equivalent of one person trying to hold 50 jumbo jets.

The Gulf Stream off the Atlantic seaboard of the United States flows at a rate nearly 300 times faster than the typical flow of the Amazon river, the world’s largest river.

The Gulf Stream Moves A Crazy Amount Of Water, Like A River In The Sea!

The Ocean’s Contents

The worlds oceans contain nearly 20 million tons of gold

A new form of life, based on chemical energy rather than light energy, resides in deep-sea hydrothermal vents along mid-ocean ridges

A swallow of seawater may contain millions of bacterial cells, hundreds of thousands of phytoplankton and tens of thousands of zooplankton

The grey whale migrates more than 10,000 miles each year, the longest migration of any mammal

More than 90 percent of the trade between countries is carried by ships and about half the communications between nations use underwater cables

More oil reaches the oceans each year as a result of leaking automobiles and other non-point sources than was spilled in Prince William Sound by the Exxon Valdez

Fish supply the greatest percentage of the world’s protein consumed by humans.

Eighty per cent of all pollution in seas and oceans comes from land-based activities.

By 2011, 80 per cent of people will live within 60 miles of the coast.


Plastic waste kills up to 1 million sea birds, 100,000 sea mammals and countless fish each year. Plastic remains in our ecosystem for years harming thousands of sea creatures everyday.

Although coral reefs comprise less than 0.5 per cent of the ocean floor, it is estimated that more than 90 per cent of marine species are directly or indirectly dependent on them.

Tropical coral reefs border the shores of 109 countries, the majority of which are among the world’s least developed. Significant reef degradation has occurred in 93 countries.

There are about 4,000 coral reef fish species worldwide, accounting for approximately a quarter of all marine fish species.

Nearly 60 per cent of the world’s remaining reefs are at significant risk of being lost in the next three decades.

The major causes of coral reef decline are coastal development, sedimentation, destructive fishing practices, pollution, tourism and global warming.

Less than one half a per cent of marine habitats are protected — compared with 11.5 per cent of global land area.

The High Seas — areas of the ocean beyond national jurisdiction — cover almost 50 per cent of the Earth’s surface. They are the least protected part of the world.

Although there are some treaties that protect ocean-going species such as whales, as well as some fisheries agreements, there are no protected areas in the High Seas.

More than 3.5 billion people depend on the ocean for their primary source of food. In 20 years, this number could double to 7 billion.

Populations of commercially attractive large fish, such as tuna, cod, swordfish and marlin have declined by as much as 90 per cent in the past century.

The blue whale can grow up to 30 metres in length; the heart alone can be the size of a car. By the early 1960s blue whales were nearly extinct, but in 1966 whaling was banned and there are currently around 10,000 blue whales in existence.

It Makes Me Sad To Think That This Huge Creature Could Ever Be Threatened By Man.

Each year, illegal longline fishing, which involves lines up to 80 miles long, with thousands of baited hooks, kills over 300,000 seabirds, including 100,000 albatrosses.

As many as 100 million sharks are killed each year for their meat and fins, which are used for shark fin soup. Hunters typically catch the sharks, de-fin them while alive and throw them back into the ocean where they either drown or bleed to death.

Final Thoughts

…and you can now pick your jaw up off the floor because that’s the end of the wonder-fest. If you’re like me you will feel a mixture of emotions having read the above articles – you will probably feel a strong sense of awe at the sheer scale of the big blue, but you might also feel a touch worried about the fragility of the ecosystems that the ocean supports. I, for one, didn’t realise that blue whales had almost went extinct, that made me really angry and sad at the same time, I love blue whales and it is my greatest wish that I should get to dive with one someday. The final fact about the shark de-finning was place last for a reason – to give you a real idea of what our race is capable of. I urge you to go and research the plight of sharks further, one organisation I recommend is Sea Shepard, a very active anti-over fishing group that really do make a difference.

Do you have any interesting ocean facts that I’ve not listed here? Are you as enraptured by the sea as I am? Do you feel a burning sense of curiosity that makes you want to go diving right now? Are you as disgusted with the over fishing and shark finning as I am? Please share your thoughts in the comment section below.

Happy (factual) Bubbles!

By Jamie Cambell

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  • Brandon said:

    Great article! Lots of interesting information. I completely agree about de-finning sharks, and current fishing methods. Everyone is so worried about the bottom line that no one takes into consideration (or just don’t care) what the effect is on the environment. Well, the fact is that if they continue down their current path chances are they will completely destroy the very ecosystem that supports them. People can be so shortsighted… it is truly depressing.


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