Deep Sea, High Pressure


I brought a second suitcase on this voyage. It was filled with cups!

So, why would I bring a whole suitcase full of cups all the way from Rhode Island, USA, to Punta Arenas at the southern tip of Chile, and then on to a research ship bound for the wild Antarctic?

To make shrunken cups, of course!



What is a shrunken cup?

We take a simple foam coffee cup and decorate it with waterproof markers. (Some people even cut shapes. We’re curious to see how those will turn out!)

Scientists from the Night team decorating cups [Credit: Marlo Garnsworthy]
Then we put the cups in a mesh bag, attach them to oceanographic equipment, and send them to the bottom of the ocean. When they come back…

Bags of cups! [Credit: Lee Stevens]
Technicians attach bags to the camera [Credit: Lee Stevens]
…they have shrunk.

Shrunken cups! [Credit: Lee Stevens]
Why do they shrink?

Have you ever swum to the bottom of a swimming pool and felt the water pushing on your ears and face? Have you swum with a snorkel and felt it’s more difficult to breathe? That’s because the deeper you go in water, the greater the water pressure. Water pressure is the force water exerts on things around it.

At sea level, air pressure—the force air molecules exert on things round them—is about 15 pounds per square inch. We don’t even notice it because we are so used to it. But the pressure of water is greater and increases the deeper you go. It increases by nearly 15 pounds per square inch for every 33 feet (10 meters) of depth.

At the bottom of the Southern Ocean where we are—where the seafloor is about 10500 feet/3200 m meters deep—the pressure is so intense that creatures not specially adapted would be crushed. That includes humans, who can only go down to this depth in a specially reinforced deep-sea submersible.

So, when a foam cup (which is made from Styrofoam beads puffed up with air) is put in this high-pressure environment, all the air is pushed out.

The result? Shrunken cups!


[Credit: Marlo Garnsworthy]
This is a favorite activity for scientists to commemorate ocean voyages. Students from Curtis Corner Middle School and South Kingstown High School in Wakefield, Rhode Island, had the chance to participate in this activity. When I return to Rhode Island, they’ll get a unique souvenir made by them and the intense water pressure of the deep Southern Ocean, but this time, my suitcase will only be a quarter full!

Education & Outreach Officer for Exp 382 & Exp 390 I am a children's book author, an illustrator, and an editor, writing teacher, and science communicator. Outreach Officer for Antarctic research cruise NBP17-02, IODP Expeditions 382 & 390.
More articles by: MGarnsworthy

1 Comment

  1. Love that you went the extra mile (or thousands of miles) for kids! My students love these kinds of demonstrations!

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