February 2012: The Ins and Outs of the Dry Suit, Osezaki, Shizuoka, Japan

Saturday February 11th 2012

Women and dry suits are apparently a match made in heaven. Dry suits are good for us because we get colder much easier than men do, because the rate in which blood vessels near the surface of the skin constrict to retain heat happens much faster and more often for us than it does for men. We also have a much larger surface area over which to lose heat. Temperature aside, when the dry suit is removed we are “dry,” which lets us skip a shower and just wash our hair, saving plenty of time.

With this, I headed to Osezaki in Shizuoka Prefecture in early February for my first dry suit dive this year. Osezaki is one of the most tranquil and isolated locations on the Izu Peninsula, offering great views of Mt Fuji on a clear day and access into the water from a beach and dive school located across the sand where divers can set up and store their equipment. My dive group offer most of their training down in Osezaki, and speak highly of the abundant marine life, schools of squid and many other creatures you can spot.

Underneath my dry suit I wore some plain yoga pants and some insulated undergarments (turtlenecks and leggings). The first thing I noticed upon donning the suit was how loose it was, with tight seals at the wrists, necks and ankles to keep water out. The suits themselves hold air inside the material, and are mainly worn when operating in very cold water, diving for long periods of time and when the diver won’t be moving around much, for example when remaining still to take photos.

During the dive, buoyancy and weight control were the hardest and most different to diving in a wetsuit. Because of water pressure upon descent, the air and the clothing between the suit and your skin compresses, and you can really feel it. This is called “squeeze.” It feels weird and even painful, but pressing the inflate valve located on your chest puts air into the suit from your tank, and relieves the feeling. The valve is connected to the tank via a low-pressure hose. The dry suit can also act as a BC. It’s easy to revert to back to the BC to help with buoyancy, but using two separate valves for more air is just confusing, so it’s more convenient to put air into the dry suit and leave the BC as an emergency life vest.

We also learned how to vent air using the exhaust valve on the left arm. To make sure all the air leaves the suit, the valve is located at the upper left arm, so we practiced lifting our left shoulder and elbow. It’s also possible to vent air automatically. Rotating the actual valve (which I could do on my dry suit) will allow air to escape when pressure in the suit is a little over ambient pressure.

I needed quite a lot of weight to descend smoothly (around 11kg) but having the minimum amount will allow you to add a minimum amount of air to your suit to control buoyancy. The weight belt can also help minimize the amount of air that goes towards your legs and feet.

Of course a dry suit keeps you warm and you can choose what you wear underneath and have some control over your level of comfort.  But they cost a lot more than a wetsuit, and maintenance is expensive too.  As I found, divers require some additional skills and more work on buoyancy (while in a wetsuit you don’t have to worry much about this) and the suit is quite bulky.

Dry suit information aside, Osezaki was a top dive site with an abundant marine life. Visibility was surprisingly good, and immediately upon descent we began swimming downwards across the sand until we reached some concrete boulders teaming with sea urchins and various species of small critters. The bay’s calm waters are ideal for training with many sheltered and calm areas.  There is also plenty for the more experienced diver.  Deeper down are large soft corals, sea whips and schools of squid which some of the others spotted but I was (and needed to be) focused on my dry suit so we stayed at around 12-13m and had a nice cruise around. As I hadn’t dived in a while, I had some minor ear clearing problems but was soon able to reach the bottom to practice venting air from the dry suit, and on the ascent relaxed a lot more, becoming completely mesmerized by a huge school of red fish with large dark eyes swimming among the concrete boulders just above the sea urchins.

I much prefer the tropical marine environment over colder waters, but was pleasantly surprised at how comfortable the dry suit was, and how the overall feeling underwater is not much different to diving in warmer environments.  I can see why women would prefer dry suits, but shorter hair is much better than long hair, to get the suit over your head through the tight neck seal.

About Rising Bubbles

Based in Bristol, UK, I am a freelance writer and consultant working on Japan’s aquaculture and fisheries development. My work focuses on issues related to sustainability, research, gender, technological advancements, adaptation and resilience. I have a keen interest in the recovery of aquaculture in the Tohoku region, following the Great East Japan Earthquake and Tsunami of March 11th, 2011, and provide news stories, features and reports from Japan for national and international seafood and fisheries media. While living in Tokyo between 2006 and 2017, I worked as a freelance writer on Japan’s aquaculture and marine-related subjects, in particular scuba diving. My blog began in 2011 as a comprehensive guide to diving in Japan. I have enjoyed exploring Japan’s waters extensively and became a certified Dive Master in August 2015. I hold an MSc in Sustainable Aquaculture from the University of St Andrews, and a BA in Japanese and French from the University of Cardiff, UK.
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