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.

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

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

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

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

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"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."

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

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

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

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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.

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

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"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.

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