Our Seas

What’s in our Seas and Oceans?

Guest contributor Tracerco gives us a tour under our seas and oceans

The world is covered by 321,003,271 cubic miles of water, according to NOAA’s National Geophysical Data Centre’s estimates. That’s around 71% of the globe. With such a massive span, it’s no wonder so many of us wonder what is under the sea. Take a tour to the depths with Tracerco!


There’re already hundreds of thousands of known living creatures that call the ocean their home. But there’s many more yet to be found, with some scientists predicting there could be millions of life forms in the sea. Plus, there are around 4,000 species of coral reef fish found across the globe — that’s close to a quarter of all of the world’s marine fish species—though be aware that a millilitre of ocean water contains close to 1 million bacteria and 10 million viruses.

Magnificent sights & amazing depths

The deepest discovered area of the planet’s oceans is the Mariana Trench. Located in the western Pacific Ocean and to the east of the Mariana Islands, the deepest point found here measures in at an estimated 11,000 metres — or 36,000 feet. The average depth of the Earth’s oceans is also 3,720 metres — or 12,200 feet.

The sea is home to the world’s longest mountain range too. Named the Mid-Oceanic Ridge, this mountain chain stretches for more than 56,000km across and covers parts of the Atlantic Ocean, the Indian Ocean and the Pacific Ocean. Meanwhile, Earth’s highest mountain in the ocean is the Mauna Kea. Found off the coast of Hawaii, the mountain rises for 10,203 metres (33,474 feet) from the ocean floor, with 4,170 metres (13,680 feet) viewable above sea level.

The sea also holds the world’s largest natural structure. This is the Great Barrier Reef — it measures around 2,600km and is so huge that it can be spotted from the Moon.

The Gulf of Mexico has brine pools and underwater volcanoes littering its ocean floor, the latter of which erupt methane and mud instead of lava. There’s also underwater hot springs found across the Earth’s oceans, where water with temperatures of 650°F shoot out — that’s hot enough to melt lead.

National Geographic reports that we have only mapped 5% of our oceans, which is far less than we have mapped of Mars.


The combined number of artefacts and historical items in the world’s museums could not match the amount of historic remnants hidden in the sea. There is almost 20 million tons of gold within the Earth’s oceans too — if all which was suspended was mined, there would be enough to give each person on the planet around 9 pounds of gold.

The treasures littering the ocean floor also total around $60 billion.

Also, the seas hold 50 quadrillion tones of dissolved solids, such as calcium salts, magnesium salts, sodium salts, and potassium salts, according to predictions by field experts.

But the ocean has more than just treasure and salt; unfortunately, the sea is home to 14 billion pounds of rubbish thrown into the waters every year. A lot of this is harmful plastic too.

Trade & communication

More than 90% of the world’s import and export trades are deal with via the sea, and nearly 50% of communications between nations makes use of cables found under the water, including subsea technology. It’s important then to maintain these communication lines with expert subsea pipeline inspection services.








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