While all the oceans are interconnected in one global ocean, this vast body of water is geographically divided into five named oceans: the Pacific Ocean, the Atlantic Ocean, the Indian Ocean, the Arctic Ocean, and the Southern (or Antarctic) Ocean. The Pacific Ocean is the largest, while the Arctic Ocean is the smallest.

Fun fact: There can be some resistance to mixing in some spots where the Atlantic Ocean and the Pacific Ocean meet! The water in one ocean may be saltier, cleaner, or colder than the other, so it may take more time for the waters to mix together. This can create a gradual gradient blend of water between the two oceans!

That’s right … the majority of Earth’s surface is covered by water! And 97% of that water is found in the oceans. The ocean is so vast that much of it is still an unexplored mystery. In fact, over 80% of the ocean is completely unmapped!

The ocean generates a LOT of oxygen ... but how? Phytoplankton! These microscopic plant-like organisms float on top of the water and perform photosynthesis, which converts carbon dioxide to fresh oxygen.

Fun fact: Some types of phytoplankton are bioluminescent, meaning they can actually glow! You can sometimes catch their shimmery blue dance on coastlines along Southern California or in the Pacific Northwest.

When people think of mountain ranges, they most likely imagine towering rock formations on land. But the longest one of all, the Mid-Atlantic Ridge, actually lies beneath the ocean! This hidden mountain range stretches over 40,000 miles across the sea floor.

The ocean is extremely deep in certain places. As the ocean gets deeper, less light shines through, the temperatures start to plummet, and the pressure rises. The deepest ocean zone, for instance, is completely black and just slightly above freezing.

Here are the five zones:

• The Sunlight Zone (Epipelagic Zone) - This zone includes the surface to about 200 meters deep. About 90% of ocean life lives in this zone.
• The Twilight Zone (Mesopelagic Zone) - This zone is from 200 to 1,000 meters deep. Very little light gets to this zone… but many animals glow through bioluminescence such as lanternfish, jellyfish, and even some sharks!
• The Midnight Zone (Bathypelagic Zone) - This zone is from 1,000 to 4,000 meters. From this zone on, the ocean becomes completely dark and very cold. The only light present comes from bioluminescent organisms.
• The Abyss (Abyssopelagic Zone) - This zone is from 4,000 to 6,000 meters. Crustaceans, mollusks, sea cucumbers, and sea stars are well adapted for this zone.
• The Trenches (Hadalpelagic Zone) - This zone is from 6,000 meters to the deepest part of the ocean. Very few creatures can survive here due to its extreme environment and intense pressure.