Dive Into the Deep: Fun Facts About the Ocean

Did you know that most of our planet is underwater? The ocean covers more than 70% of Earth’s surface, yet we’ve explored less of it than the surface of the Mars! From glow-in-the-dark creatures to underwater mountains taller than anything on land, the ocean is packed with life and continued surprises. In this blog, we’ll dive into some of the coolest, weirdest, and most amazing facts about the deep blue sea. Get ready to explore fun facts about the ocean, an underwater world that’s mysterious, powerful, and full of life!

This spectacular “blue marble” image is the most detailed true-color image of the entire Earth to date. Using a collection of satellite-based observations, scientists and visualizers stitched together months of observations of the land surface, oceans, sea ice, and clouds into a seamless, true-color mosaic of every square kilometer (.386 square mile) of our planet. These images are freely available to educators, scientists, museums, and the public. — Image: “Blue Marble”, a collection of observations from NASA’s Moderate Resolution Imaging Spectroradiometer, or MODIS Credit: NASA

Fun Facts About the Ocean: The Ocean’s Hidden Highway and More!

There is only one world ocean, but five named ocean basins. The ocean basins are: the Arctic, Atlantic, Indian, Pacific, and Southern.

The ocean holds 71% of Earth’s water and 35 out of 50 of our critical mineral resources.

Our ocean is home to the biggest living thing on Earth—the Great Barrier Reef! It’s so huge that it stretches about 1,600 miles (that’s around 2,600 kilometers), and evidently astronauts can even see it from space!

Thermohaline circulation is ocean’s hidden highway that moves ocean water all around the planet. It’s driven by two things: temperature (that’s the “thermo” part) and saltiness (that’s the “haline” part).

Here’s how it works:
In some cold places, like near the North and South Poles, ocean water gets really cold and salty. Cold, salty water is heavier than warm or fresh water, so it sinks to the bottom of the ocean. When it sinks, it pushes other water around, helping it flow through the deep ocean.

Conversely, in warmer parts of the world, the sun heats the water and makes it rise to the surface. This creates a loop: cold water sinks and spreads, warm water rises and moves along the top. It’s all connected—like a slow, steady current that helps mix the oceans and move heat around the planet.

This circulation helps keep our climate stable and supports ocean life by moving oxygen and nutrients around. Pretty amazing, right?

A map of thermohaline circulation--a giant conveyor belt that moves heat around the ocean. — Image: Map of ocean (thermohaline) circulation Credit: Freepik

It’s Deep and Teeming with Life!

Most of the ocean is a little more than 2 miles deep. But the deepest spot is the Mariana Trench in the Pacific Ocean—it’s almost 7 miles deep. That’s like stacking more than 112 football fields end to end straight down into the bottom!

An illustration of the Mariana Trench--the deepest part of the ocean. It's nearly 7 miles deep. — Image: The Mariana Trench in the Western Pacific is nearly 7 miles deep. 3D illustration credit: ratpak223, iStock

Over half of the world’s oxygen is created by phytoplankton and algae in the ocean.

More than 2.2 million species of animals live in the ocean, and scientists have only explored 5% of the ocean!

The water on Earth actually has its roots in outer space. Scientists believe that some of the water in our oceans came from icy comets and space rocks that hit Earth billions of years ago. So in a way, the origins of our oceans are in the stars!

El Niño and La Niña are ocean patterns in the Pacific that change sea levels and weather around the world. El Niño brings warmer water and higher sea levels to the eastern Pacific. La Niña does the opposite—pushing warm water west and raising sea levels there instead.

A graph of El Niño (warm) and La Niña (cool) cycles. — Image: Graph of El Niño (warm) and La Niña (cool) cycles. Red = El Niño Blue = La Niña Credit: NOAA

Not So Fun Facts About the Ocean!

Shell-Builders Aren’t Happy!

The ocean absorbs about 30% of the carbon dioxide (CO2) that goes into the air, which makes the water more acidic. This makes it harder for animals like oysters, clams, sea urchins, corals, and tiny plankton to build and keep their shells.

An illustration of CO2 being absorbed by the ocean. — Image: Carbon dioxide (CO2) emissions are being absorbed by the ocean. Credit: Francesco Scatena, iStock

Image of a sick sea lion lying on the beach. — Image: Sick sea lion lying on the beach. Credit: Freepik

A mix of warmer waters plus fertilizer runoff can increase the growth of harmful algal blooms. This causing sea life to get sick and even die.

Hotter Seas, Higher Tides: The Ocean’s Warning

Graph showing the ocean is getting hotter, with heat records broken every year since 2019. — Image: The ocean is gettting hotter. Credit: NASA

In 2024, ocean temperatures hit a record 20.87°C (69.57°F), with heat records broken every year since 2019—fueling more intense marine heatwaves

Graph of sea level rise from tide gauges since 1880 and satellites since 1993 compared to global temperature. — Image: Graph of sea level from tide gauges since 1880 compared to global temperature. Credit: NASA

Graph of sea level rise since 1993. Since then, sea level has risen 102.4 millimeters. — Image: Graph of sea level rise since 1993. Credit: N

How We Can Help

Share our information with friends and family.

Support renewable energy.

Conserve energy.

Minimize plastic consumption.

Choose sustainable seafood.

Join a beach cleanup.

Donate to organizations working to protect the ocean, like Ocean Conservancy and Surfrider Foundation.

Our environment is facing more threats than ever before, so we need to support agencies like NOAA and the EPA—not take money away from them. After all, they help protect the air we breathe, the land we live on, and the water we drink. Now’s the time to speak up for the programs and people who keep our planet safe.

Don’t miss the rest of our ‘Understanding Science” posts right here!