Ocean Facts for Kids

The deepest part of the ocean isn't just deep-it's unbelievably deep! It's called the Challenger Deep in the Mariana Trench.

It plunges to a depth of 10,971 meters (that's about 35,994 feet!).

If you took Mount Everest, the tallest mountain above sea level, and dropped it in, the peak would still be over 2 kilometers underwater!

We know more about the surface of Mars than we know about this deepest part of our ocean floor!

Think about all the water on Earth-in rivers, lakes, clouds, and even in you! Ready for this? About 97% of all that water is in the ocean.

That means only about 3% is the freshwater we can easily use for drinking and swimming.

The Southern Hemisphere is super wet, with oceans covering 81% of its surface area!

That's why Earth is nicknamed the 'Water World'!

The Great Barrier Reef is the biggest single structure made by living things on Earth-it's built by billions of tiny coral polyps!

It stretches for over 2,300 kilometers along the coast of Australia.

Its total area is about 348,700 square kilometers (or 133,000 square miles).

That makes it bigger than countries like Italy or Malaysia! Wow!

Blue whales are the largest animals ever, so they need the biggest hearts! Their heart can weigh about 400 pounds.

That's as heavy as a small car, or about 400 human hearts combined!

When they dive deep, their heart rate slows to just 2 to 10 beats per minute (bpm).

The sound of one beat is so loud it can travel over two miles through the water!

Forget speedy cars-the Black Marlin is often called the fastest fish alive, cruising at incredible speeds!

Some famous fishing reports claim they can swim nearly 82 miles per hour (132 km/h)!

Even more cautious scientific estimates suggest a top speed of 36 km/h (22 mph), which is still super fast for a fish.

They need that speed to catch dinner and escape bigger ocean bullies!

Way down where sunlight never reaches-past 300 meters (1,000 feet)-it's totally black! But life doesn't stop.

In fact, scientists found that up to three-quarters of animals in the dark zones can create their own light through a chemical reaction-this is called bioluminescence.

They use this light to find food, hide from enemies, or even find a friend!

Most of this light is blue, because blue light travels best through water.

Under the sea, there are underwater volcanoes called hydrothermal vents that shoot out super-hot water!

This water can reach temperatures up to 400 degrees Celsius (752 degrees Fahrenheit).

That is hot enough to melt lead, but some creatures like tube worms and shrimp live right next to them!

They survive because bacteria use the chemicals in the water for energy, not sunlight.

When we look for the absolute oldest signs of life on Earth, we look in the ancient oceans, especially near vents!

Scientists found microscopic fossils of bacteria in rocks in Quebec that are at least 3.77 billion years old.

These rocks likely formed near deep-sea hydrothermal vents, suggesting life started there super early.

That's over three-quarters of the age of our entire planet!

Ocean currents move water all around the globe, distributing heat and nutrients. They are like giant, slow-moving rivers in the sea!

While surface currents like the Gulf Stream are faster (up to 2 meters per second), the deep currents are still powerful.

The fastest deep ocean current measured, the Antarctic Bottom Water, moves at an average of 7.9 inches per second (0.20 m/s).

This massive, cold current even circles the entire continent of Antarctica!

You might think you know a lot of fish, but scientists have described nearly 34,000 different species so far!

And get this-they discover about 300 to 500 NEW species every single year.

The ocean is so huge, scientists guess that up to 91% of all ocean species might still be waiting to be discovered!

That means you could discover the next coolest fish for kids to learn about!