Can a jumbo jet fit on a basketball court?

If you dropped a basketball into the Mariana Trench, it would never reach the bottom intact. The pressure at 36,000 feet deep is roughly 16,000 pounds per square inch, which is the equivalent of having an elephant stand on a postage stamp. Long before the ball hit the seafloor, the air inside would be compressed so violently that the rubber would likely implode into a tiny, shriveled mass.

Water at this depth acts differently than the water in a swimming pool. It is so heavy that it actually compresses itself, occupying about 4% less volume than it does at the surface. If you could somehow bring a gallon of trench water to the surface instantly, it would expand like a released spring.

Because the pressure is so extreme, the boiling point of water changes. Near hydrothermal vents on the ocean floor, water can reach 700 degrees Fahrenheit without ever turning into steam. It stays liquid even at temperatures that would boil water on land, becoming what scientists call superheated water.

Styrofoam cups sent down on research submersibles come back the size of thimbles. The air pockets inside the foam are crushed flat, leaving a dense, hard plastic nugget. Air-filled materials like Styrofoam are crushed into dense nuggets, though solid materials like wood are less drastically affected.

Even more unsettling is what happens to bones. At these depths, shells made of calcium carbonate can dissolve, though fish bones—made of calcium phosphate—are more resistant.