The ocean is the biggest thing on Earth and the least visited. These questions reward the people who look at the blue parts of the map. Lock in each answer before revealing.
How much of Earth's surface does the ocean cover?
About 71%.
What is the largest animal ever known to have lived on Earth?
The blue whale — larger than any dinosaur we know of, and still here.
What is the deepest known point in the ocean?
Challenger Deep in the Mariana Trench — about 36,000 feet down.
What is the longest mountain range on Earth?
The mid-ocean ridge — roughly 40,000 miles, almost all of it underwater.
Which ocean is the largest?
The Pacific — it covers more area than all of Earth's land combined.
How much of the ocean floor has been mapped in high resolution?
Only about a quarter — most of the deep sea remains unmapped in detail.
How much of Earth's oxygen comes from the ocean?
At least half — most of it from drifting phytoplankton.
Why do swimmers float so easily in the Dead Sea?
It's nearly ten times saltier than the open ocean — the dense water pushes you up.
What is the fastest fish in the sea?
The sailfish — clocked near 68 mph in short bursts.
How crushing is the pressure at the bottom of the Mariana Trench?
About 8 tons per square inch — over 1,000 times the pressure at sea level.
The Great Barrier Reef sits off the coast of which country?
Australia — it's the largest living structure on Earth.
What did sailors likely mistake for mermaids?
Manatees and dugongs — Columbus himself logged a sighting.
If the mid-ocean ridge landed for you, congratulations: you know Earth's biggest mountain range, and you've never seen it.
