For several months now, a trend among the marine scientists has appeared on Twitter. They started posting pictures of their Styrofoam cups that went for a “little” dive, symbol and souvenir of the memorable expeditions they just had.
What is it? A foam cup, a polystyrene cup, a Frigolite cup, a Styrofoam cup … Or anything made of foam! They are designed, drawn, or/and signed (with waterproof pens) during a cruise.
Why? How ? This material is made of plastic and 95% of air. When it dives into deepness, the pressure exerted on the cup will shrink the material by diminishing the air space proportionally. At the surface, the atmospheric pressure is 1 bar. It increases of 1 bar every 10 meters. Therefore, at 10 meters, the pressure is 2 bars and at 30 meters, the pressure will be of 4 bars. The air space in the cup is divided by 2 at 10 meters and by 4 at 30 meters! While reaching some depth, the pressure will be so intense, that the airspace could be considered as negligible and only the volume of the plastic material stays intact.
Finally, from about 10-15 cm tall cup, we obtain a ~4 cm tall cup without any air space.
It is always a great time on the cruise to relax at drawing on our cups. We all get exited when they come back from depth, 1000 m, 3000 m, or even for the luckiest ones, going back from a trench at more than 5000 m! They were attached in a bag on any instrument/device going into water, such as the CTD rosette or the ROV (remote operated vehicle).
Some examples from scientists at the National Oceanography Centre!
David Price, PhD student, at the Whittard Canyon refers to the iconic Boaty McBoatFace:
Iain Stobbs, PhD student, from the TAG Hydrothermal Field on the Mid-Atlantic Ridge:
Dr Isobel Yeo, myself, and some colleagues on board the Celtic Explorer for the TOSCA expedition where we see before and after: