When I told you about my last dive, it was a new adventure for me because I had never been under the ice before. Other than the cold temperature, however, all of the gear and SCUBA diving techniques were familiar to me. SCUBA divers use some standard clothing and equipment, and you probably know most of the basics. Let's talk quickly about each key piece:
Suit:
We wear some sort of suit, either wet or dry, to keep us warm. A wetsuit is a tight suit made of neoprene that traps a thin layer of water between the suit and your skin and therefore helps to keep you insulated from most of the cold. A drysuit is a suit that you actually wear over your clothes, and it has neoprene or latex seals at your wrist and neck to keep the water out. I'll bet you can guess why we use drysuits while diving in Antarctica! I don't want any of that freezing cold water touching my skin! Of course, you can dive in Antarctica in a wetsuit, and the first divers down here did. However, a wetsuit makes you much colder and your dives have to be much shorter!
Fins:
Most divers use fins to help them swim around more efficiently underwater.
Mask:
A SCUBA mask is used so that we can see underwater. They work just like goggles, but they cover your nose as well. It helps to cover your nose so that you don't try to breathe any water up into it :)
BCD:
A BCD is a Buoyancy Compensation Device. It is often shaped and worn like a vest. It holds a pocket full of air that the diver can either add air to or dump air from. Using this vest, the diver can become neutrally buoyant. That just means that you don't sink and don't float: you can remain suspended in the water column. Being neutrally buoyant is probably the most important part of SCUBA diving. It keeps you from crashing into the bottom, from sinking too rapidly, or from floating too quickly to the surface, all of which can be dangerous! When we dive in drysuits, we don't actually use a BCD vest because our drysuits serve as the air pocket. I can control the amount of air in my suit to make myself neutrally buoyant.
SCUBA tank and regulator:
A SCUBA diver does need to breathe underwater and that is why we carry a tank of compressed air. We breathe that air through something called a regulator, which delivers the correct amount of air to your mouth when you breath in.
If you want to check out more details about SCUBA diving, you can start here: http://en.wikipedia.org/wiki/Scuba_diving
So what is different about diving in Antarctica? I already mentioned that we wear drysuits rather than wetsuits. We also really layer up under our drysuits. I wear wool long pants, a wool long sleeve shirt, thick wool socks, a thinsulate jumpsuit (thinsulate is kind of like fake goose down...it insulates really well), thinsulate booties, and some thin glove liners. My drysuit goes on over all of that. It has a seal at the neck to keep the water out. I have plastic gloves that actually attach at the wrists of my suit so that my hands stay dry and warm. On my head I wear a thick neoprene hood that actually keeps my head fairly dry.
Now, the really exciting part of today is that instead of wearing a SCUBA mask and carrying a big tank of air, I wore a full face mask and dove on surface supply air! Here you can see me being taught some of the finer points of the face mask (and no, I don't wear my hat underwater, but I do wear it in the dive hut to keep my head warm):
The full face mask is kind of like a big metal helmet with a clear area through which you can look out. We attach a long tether to the mask that sends air from tanks on the surface down to the mask. The small tank that you see on my back is some extra air in case the tether has a problem. That would provide me with enough air to get back to the surface. The advantage of the full mask down here in Antarctica is that it keeps our heads, and therefore ourselves, much warmer than diving with just a regular SCUBA mask. The full mask also lets us talk to the person on the surface! There is a microphone inside the mask, and the sound is carried up a cable that is part of the tether.
Here you can see me in all of the gear for the first time (I think I look kind of like Darth Vader):
Let me tell you, diving with that big thing on your head is quite an experience. I wasn't really prepared for just how heavy it was! Diving in a drysuit is hard work to start with. Having a big suit filled with air makes you very buoyant. In fact, if I put my drysuit on and just jump in the water, I will float. To make ourselves neutrally buoyant we add weights. In salt water, I have to wear a vest that has 40 pounds of weight to make myself neutrally buoyant. Adding the facemask traps even more air, so I had to add an extra 5 pounds! Then you add the weight of the mask itself, and I have difficulty climbing in and out of that dive hole! We really have to work as a team to help each other get in and out of the ice.
I know you probably want to know about all of the exciting things that I saw on this dive, but I have to confess that this trip under the ice was mostly about learning how to use the equipment. I can tell you that the ice was much thicker here, which made going through the ice quite exciting. Because the ice was so thick, it was very dark underwater. I took a flashlight down with me so that I could see what was on the bottom. It was not completely dark, and looking out into the blue was gorgeous because of the way the ice sends shafts of light down through it. There also were lots on interesting creatures on the bottom, even though the locals don't consider this dive site to be very exciting. There were lots of anemones, worms, sponges, soft corals, sea stars, sea spiders, etc. The waters around Antarctica that I have seen so far are stunning!
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