Eleven Hundred Atmospheres

In the lab below the deck, a scientist named Yara was setting up a demonstration for Polly. She had two cups. One was big. The other was very small.

"Same cup," Yara said. "But the small one went to the bottom of the trench last week. It came back like this."

Polly looked closely. The little cup looked like the big cup, but tiny. The walls were thick and hard.

Yara explained. Styrofoam is mostly air. At the bottom of the sea, the air gets pushed out. The plastic gets pressed together.

Polly hopped around the bench, looking at the small cup.

"The submersible is fine," Yara said. "Because there is air inside it too. The danger is not being crushed. The danger is a tiny leak."

She showed Polly another test. She put a marshmallow in a glass jar. Then she pumped out the air.

The marshmallow grew bigger. It doubled in size. Then it grew even more. Polly's eyes went wide.

When the air came back, the marshmallow shrank again. "The deep sea does the opposite," Yara said. "It crushes things."

Then Yara showed Polly something else. Deep in the sea, some gases stay frozen with water. They form a kind of ice. The ice is stable only under pressure.

If you bring this ice up, it falls apart. Yara had some in a freezer. It looked like dirty ice.

"Water at the bottom is heavier than water up here," she said. "Sound goes faster in it. The deep sea is a different world." Polly looked at the tiny cup. A different world indeed.