Interesting Ocean Facts to Engage Your Children

The ocean is fascinating and is vital to our ecosystem and so much of it is yet to be explored.

In fact, we know more about the surface of Mars than we do about our own sea floor.

In this guide, you’ll learn fun, mind-tingling facts about the deep blue and what lies beneath. 

It’s All Connected

world ocean


You’ll often hear about “the Pacific Ocean” or “the Atlantic Ocean.” But really, it’s all connected and it’s all just one huge body of water.

We humans break things down by region so it’s easier for us to keep straight. We’ve divided the ocean into the Pacific, Atlantic, Indian, Arctic and Southern Oceans.

But that is a completely manmade concept. All of these waters flow into each other, without any kind of natural separation.

The Ocean is Big, Really Big

The ocean takes up 78% of the Earth’s surface, about 139,434,000 square miles (361,132,000 square kilometers).

Let’s think about it this way, the United States is 3,796,742 square miles (9,833,520 square kilometers). So the ocean is more than 36 times bigger than the US.

If you took all the land, on the entire planet, and added it up, the ocean is still 6.5 times bigger!

Like I said, that’s really big!

The Ocean is the Biggest Habitat Anywhere on Earth

Not all of the planet can support living things. Deep underground, there isn’t enough air to breath and it would be much too hot for anything to live.

High in the upper atmosphere, it’s too cold and there is not enough oxygen to sustain life.

All of the parts of the Earth in between, that can sustain life, are known as the biosphere.

The ocean makes up 99% of the biosphere for the entire planet.

Just think about that for a minute. When you walk outside, all of the land and sky you see, or will ever see in your whole life is just 1% of the biosphere.

There is literally 99 times more livable space under the ocean than on the land you see every day.

The Most Species

It makes sense that the ocean holds a lot of living creatures since it takes up so much of the planet.

Currently, there are over 225,000 species of living creatures living in the ocean that have been identified and described by scientists.

It’s thought that there could be as many as 25 million more that haven’t yet been studied!

Not Everything That Lives in the Ocean is a Fish

There are many different kinds of animals that live in the ocean. Sea turtles and sea snakes are reptiles.

Shrimp, crabs and lobsters are crustaceans.

Dolphins, whales, purpoises, seals, sea lions and walruses are all mammals.

So just because it swims, and lives under the sea, doesn’t automatically mean that it’s a fish.

It’s Home to the Biggest Animal Ever

The ocean doesn’t just have the most species of animals, it also has the biggest.

As far as we know, the blue whale (Balaenoptera musculus) is the biggest animal that has ever existed. It’s even bigger than the largest species of dinosaurs were.

It grows up to 98 feet (28.5 meters) and can weigh as much as 130 tons.

Length of a blue whale compared to school bus, cars, and baseball bats

The World’s Tallest Mountain

You’ve probably been told that Mount Everest is the tallest mountain on Earth.

This isn’t actually true.

Everest has the highest altitude anywhere on Earth, meaning the distance from sea level to its highest point. From sea level, Mount Everest is 29,029 feet (8,848 meters) tall.

But, in Hawaii, there is an extinct volcano called Mauna Kea.

From sea level to summit, the peak is only 13,803 feet (4,207.3 meters) high.

But the base of Mauna Kea isn’t at sea level, it’s over 19,000 feet (6,000 meters) underwater. If you measure it from its base on the ocean floor, Mauna Kea is 33,000 feet (10,000 meters) tall.

That makes it the world’s tallest mountain, even if most of it is under the ocean.

The World’s Deepest Canyons

There are long, narrow canyons far below the ocean’s surface called trenches. These trenches are the deepest places on Earth.

Ocean trenches are found all over the world. They form when two plates in the Earth’s crust meet and one plate is forced to slide beneath the other. This creates a huge wrinkle that plunges downward.

The deepest spots in the seafloor are in the Marianas Trench in the Pacific Ocean. It’s shaped like a crescent and is 1,580 miles (2,550 kilometers) long.

Its lowest point is called the Challenger Deep, it’s bottom is 36,070 feet (10,994 meters) below sea level, almost six times deeper than the Grand Canyon.

If you sank Mount Everest into the Challenger Deep, the tip of the mountain would still be over 2 kilometers below the surface of the water.

Light Can’t Always Get to the Bottom

The ocean is so deep in places that light can’t get anywhere near the bottom.

The ocean is divided into three zones when it comes to light.

Between the water’s surface and 200 meters (656 feet) down is called the euphotic zone. There’s plenty of sunshine at these depths and algae and plants can grow here.

From 200 meters to 1,000 meters (3,280 feet) below the surface, is known as the dysphotic zone. Light is very dim here and it gets darker the deeper you go. But at least there is a little bit.

Still, plants and algae can’t grow in this zone since the light is so weak.

Below 1,000 meters is the aphotic zone. There is no light past this point at all.

We Have Not Explored All of the Ocean

Humans have sailed on the surface of the entire ocean. And we’ve made detailed maps of all the coastlines and features of the shallow waters, like where coral reefs are.

But, we have not explored much of the deep ocean at all. In fact, more people have been to space than to the deep ocean.

536 people have traveled to space, 12 of them have gone all the way to the moon, but only 3 people have ever been to the deepest parts of the ocean.

Pressure Increases with Depth

In any body of water, the deeper you go, the more the water pressure increases.

This is because the weight of the water above you is constantly pressing down on the water below.

The deeper you go, the more water there is above you, so the weight just keeps increasing.

This pressure can become so great that it can crush a human body, or even some submarines.

Animals that live in the deep ocean have special adaptations that let them survive in these high pressure conditions. But there’s no way for a human to do it without special equipment.

The extreme pressure found in the deep ocean is one of the main obstacles that has kept mankind from exploring more of it.

The Ocean is Always Moving

Even when it seems like the water is very calm, the ocean is always in motion.


Ocean waters don’t always stay the same depth. As the Moon orbits around the Earth, its gravity pulls ocean water towards it. The gravity of the Sun can also have an effect on ocean waters.

The ocean being pulled towards the moon and sun causes sea levels to rise and fall, something known as ocean tides.

Water on the side of the Earth that is closest to the moon gets deeper, sometimes by as much as 20 feet (12.2 meters).

Ocean water on the two sides that are perpendicular to the Moon get much more shallow.

When water is deeper, it’s called high tide. And when it’s more shallow, it’s called low tide.

Tides are the easiest to see along the shore, especially compared to stationary things like docks, bridges or rocks. But even the deepest parts of the ocean have low and high tides.


The surface of the ocean is very rarely still.

As wind blows over the water, it pushes against the surface, causing waves.

Waves can be tiny ripples that are only a few inches tall or giant 100 foot (30 meter) swells. Waves can travel for hundreds or thousands of miles before they eventually stop when they crash into shore.


Ocean water doesn’t just stay in one place. It’s constantly moving and flowing around the globe.

Currents are the movement of ocean water both at the surface and in the deep ocean.

On the surface, currents are powered by wind and tides.

Deep ocean currents are driven by changes in water density and salinity, the level of salt dissolved in the water.

Ocean currents have a huge effect on weather patterns on both land and sea.

Surface currents turn in big circles, called gyres, that move clockwise in the northern hemisphere and counterclockwise in the southern hemisphere.

Many Sea Creatures Make Their Own Light

Leidy Comb Jelly

Some sea creatures can make their own light. The comes from a chemical reaction called bioluminescence.

Sea creatures use bioluminescence for different reasons.

Way down under the ocean surface, where there is no sunlight, some creatures use bioluminescence to attract prey.

The deep sea angler fish (Ceratias hobolli), has a special “fishing lure” attached to its head.

It kind of looks like an antennae with a glowing worm on the end.

Smaller fish are attracted to the lure and swim in closer. Then the angler fish gulps them into its mouth for dinner.

Some squids use bioluminescence for something called counterillumination. They light up their bellies so predators below them don’t look up and see their dark shape against the light coming from the surface.

Other creatures use bioluminescence to attract mates, distract predators or warn others that their territory is being invaded.

Plastic Debris is a Problem

Each year, millions of tons of plastic ends up in the ocean. Some gets tossed over the side of ships and some is from trash thrown on beaches.

But most of it gets washed away from city streets and landfills each time it rains.

Even if you live really far from the ocean, plastic trash from your city or town can still end up getting washed out to sea.

Heavy rain washes plastic items, like empty water bottles, plastic straws, or lids, into streams and rivers.

The trash keeps flowing downstream until it eventually reaches the ocean.

Also, in landfills, plastic gets crushed by machines that turn over the huge mountains of garbage. This breaks it into smaller and smaller pieces, called microplastic.

It’s very easy for microplastics to get caught up in rainwater and end up washing into the ocean.

Also, larger pieces of plastic debris in the ocean rub against each other and put off microplastics.

Plastic waste that ends up in the ocean is very bad for the environment. It puts off toxic chemicals that are harmful to fish and other sea life.

Aquatic animals can also accidentally swallow pieces of plastic, especially microplastic.

Their bodies can’t digest it. So it ends up being a big mass in their digestive system that can eventually kill the animal.

The biggest problem is for predators.

Animals like dolphins or orcas eat fish to survive. If all of the little fish that they eat have plastic in their stomachs, then the dolphin or whale ends up with that plastic in their stomachs.

If they end up getting too much, it can kill them. In 2018, 60% of the whales and dolphins that died on beaches had eaten plastic.

That is really bad news for animals that are already vulnerable!

Some plastic trash could take thousands of years to biodegrade. So it just keeps floating around, potentially for centuries. Ocean currents push it together into gigantic garbage patches that are millions of square miles wide.

The Ocean is Becoming More Acidic

Levels of carbon dioxide (CO2) in the atmosphere are increasing. When seawater absorbs CO2, it makes it more acidic.

Scientists are worried that this could have a negative impact on ocean habitats.

If ocean water becomes too acidic, it can melt the shells of small crustaceans that are a part of plankton.

And it could keep corals from being able to grow their skeletons.

Corals not growing properly is a huge concern. Coral skeletons are what make up coral reefs. Reefs are home to 25% of all marine species and so they are incredibly important to ocean health.

Help Keep the Oceans Alive

Sometimes it can seem like there’s no hope for the ocean. But staying aware and making some simple lifestyle changes can really help to protect it.

Things you can do to help protect the ocean and all the creatures that live in it:

Recycle your plastic trash – this helps to keep plastics from being washed into the ocean and adding to the plastic garbage patches.
Support clean up efforts – there are many companies that are working to clean up plastics from the ocean.

4Ocean gathers plastic and glass debris from the coastal areas and turns it into jewelry. Each bracelet they sell pays to remove 1 pound of plastic and glass from the ocean.

Ocean Cleanup is developing technologies that would clean up huge portions of the plastic garbage patches so they can be brought to land and recycled.

Bahamas Plastic Movement teaches students about the impact of plastic marine debris and gets them involved in the cleanup effort.

Join a beach cleanup – if you live in a coastal area, there are many volunteer organizations that walk local beaches picking up trash. Even if there isn’t anything like this where you live, just grab some gloves, trash bags and a few friends. Every piece of trash you get off the beach is one less piece that gets washed out to sea.

Use reusable products – instead of relying on single-use plastic products, you can use reusable products. Refill your own water bottles, bring reusable shopping bags with you to the store and/or pack your own eating utensils from home, anything you can do to use less plastic each day. You’d be surprised at how much little changes can add up to make big impacts.

Skip the straw – you might only use a straw for an hour or so, but it can really have a lasting impact. Millions of plastic drinking straws end up in the ocean each year. Straws can take up to 200 years to decompose, that’s two human lifetimes! But, you can just not use a straw with your drink and help protect ocean wildlife. Or, if you do use a straw, make absolutely sure it gets recycled!

Just these little adjustments to your lifestyle can really help to make the ocean healthier. Everyone can contribute and do their part to help keep the ocean safe.

Even if you don’t live on the coast, the ocean is an important key to all life on Earth. It’s our job to protect it.

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Check out these fun and interesting facts about the ocean and help your kids learn more about why the ocean is so wonderful and needs help. #modestfish #ocean #environment
Katherine Morgan
Katherine Morgan

Hey, there! I'm Katherine from Northwest Florida. An aquarium specialist, I've kept tanks for over two decades, enjoy experimenting with low-tech planted setups and an avid South American cichlid enthusiast.


  1. Awesome article!! My daughter loved reading this. It was very informative and fun to read!

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