It is that time of the cruise for the sacred maritime tradition of….shrinking styrofoam cups.

I have no idea who figured out this odd pastime at sea, but the reasoning goes like this: As you move deeper into the ocean, pressure increases due to the weight of the water above you.  All of our equipment has to be rigorously pressure-tested, and is all graded to only go to a certain depth.

Styrofoam is polystyrene plastic that is formed by blowing air into  the plastic during creation.  So, what happens when you attach Styrofoam to said equipment and send it to the bottom of the sea? The increasing pressure with depth pushes the air out of the plastic, and you are left with condensed Styrofoam, sans air. In simpler terms, the pressure causes everything foam to shrink, while the metal equipment, not comprised of air, comes back up in the same shape.

Anything you draw on the cups shrinks with them. We sent down one bag of decorated foam cups, wig heads, and cubes from the science party on board, and two bags from a local San Diego middle school.


First Cat, Maitreyi, Belli and Ali prepared all the cups by filling them with paper towels and tape to maintain their shape, and then zip tying the laundry bags closed so we didn’t lose any to the ocean.


Then the Science Techs kindly zip tied them to the CTD for the deepest cast of the cruise. The cups went to 3000 m!

The cups came back a little smaller (note the difference in bag size):


The most impressive part are the before and after shots:


My head shrunk a lot at 3000 m!