Stay Puft Marshmallow Woman

"Stay Puft Kirstin!" my fiancé beamed as he attached the hose to my suit. He turned on the compressed air tank at the other end and pushed the button on my sternum to inflate the suit. It filled with air, bubbling out around me until I looked like a marshmallow woman. 

"This feels so weird!" I exclaimed, feeling my new full-body garment swell with air. My fiancé released the inflator button and stood back to look at me. 

"I think it fits," he announced. "Now raise your left arm." 


Lifting my elbow, I heard air rush out of the dump valve on the suit's left side. I slowly deflated. 


Friends, as many of you know, I learned to SCUBA dive this year. It's a great way to access habitats between the intertidal and the deep sea, explore the biodiversity around me, and get outdoors. It's my new favorite thing. Well, diving in New England is complicated by declining water temperatures in winter. Below about 50° F, it's unsafe to be underwater in just a wetsuit, so we have to use drysuits to stay insulated and warm. They're durable, thick, full-body suits that keep you insulated from the cold water around you. You're completely covered and sealed off from the water except for your head and hands.

In my (deflated) dry suit after
a recent dive. Photo by Carl Kaiser.

The catch? Drysuits are completely sealed, 
so you're basically diving in a bag of air. The air between the suit and your body compresses at depth. Water pressure increases rapidly as you descend - adding about 1 atmosphere of pressure for every 10 m (33 ft). A drysuit that feels fine at the surface will squeeze your body at depth. 

To counteract the squeezing effect, we add air into the suit. Every drysuit has a hose attached from your air tank to an inflator valve on your chest. When you push the button on the valve, air rushes into the suit. You can empty the suit by lifting your left arm and letting air rush out of the exhaust valve there. 

Let me tell you, friends, feeling a drysuit inflate around you is a very strange feeling. Underwater, it always felt like a relief - by the time I hit the inflator button on my chest, my suit was pretty tight, so it felt just like a release of pressure over my whole body. On the surface, though, I don't even know what I could compare it to. 


I did my first two drysuit training dives yesterday, and I had a fun time getting oriented to the suit. Every time I inflated it at depth, I could feel air rushing into different parts of the suit, equalizing under pressure. One of things to watch out for when diving dry is that your feet can fill with air. If you accidentally get your feet too high underwater, all the air in your suit rushes to your booties. The extra buoyancy can pull your feet even further upward, and if you're not careful, you can rocket to the surface upside-down. I never had an accident, but on my second training dive, I did manage to get my feet above my head. I grabbed onto a guide line under the WHOI pier, where I was diving, to hold myself near the seafloor, and the two instructors who were with me helped me wrestle my feet back down. There is a technique to solve foot-inflation problems yourself by somersaulting underwater and raising your left arm to dump air out. I practiced the somersaults in midwater at the end of the dive, and after a couple times, I had it down. I was grateful for the patience of the two instructors as they helped me learn to manage my gas volumes.


I'm excited to keep practicing in my drysuit and especially to use it for research projects. Winter cannot stop me!

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