Antarctica. McMurdo Sound. Ice Diving
Antarctica. Ice Diving. Mcmurdo Sound.
There’s cold-water diving. There’s icy-cold-water diving.
And then there’s Antarctic ice diving!
When she was affiliated with Moss Landing Marine Laboratories, Linda Kuhnz had an opportunity to accompany a diving research expedition to McMurdo Sound on the southern tip of Ross Island in Antarctica. “I knew for a year in advance that I’d be going, and had plenty of time to get prepped and think about the upcoming experience,” Linda began. “I’d done a lot of cold-water diving with wet suits of varying thickness, but it became clear pretty quickly that I’d have to learn to dive with a dry suit. I thought that ice diving might feel confining or claustrophobic, and wasn’t sure how I’d react. Some people who’d had the experience told me that when you drop down the ice hole—sometimes as much as ten feet deep—it can be a bit frightening.”
Antarctica is not one of the world’s most welcoming places. This is evidenced by the fact that there are no indigenous people on the continent, despite the fact that Antarctica encompasses more than 14,000,000 square miles, roughly one-and-a-half times the size of the United States! A contingent of 5,000 scientists from the twenty-seven nations that are signatories of the Antarctic Treaty maintain a year-round presence on the continent; another 25,000 or so tourists visit the warmest areas (on the Antarctic peninsula) each season. A great majority of the land mass—an estimated 98 percent—consists of ice and snow that has an average thickness of 7,000 feet; scientists believe that up to 70 percent of the world’s fresh water is contained here. During the winter months, when temperatures hover in the balmy range of –40 to –90 degrees Fahrenheit, sea water surrounding the continent freezes up to 200 miles offshore, covering an area even larger than Antarctica’s landmass. In the summer (December through March), the freeze recedes, though not so much as to precludeice diving. McMurdo Sound rests roughly 850 miles north of the South Pole, on the far western edge of the continent (or 2,400 miles due south of Christchurch, New Zealand).
Unusual Ice Diving
According to research assembled by Peter Brueggeman of the Scripps Institution of Oceanography library, the first dive below the ice of Antarctica occurred in 1902, when Willy Heinrich, a carpenter on the German craft the Gauss, descended to conduct repairs. Now as then, ice diving presents several unique challenges. First among them is breaking through the ice. This task is generally achieved with a large ice auger, which is brought out to the prospective diving site on a tracked vehicle (imagine a very large snowmobile). Holes can be quite large, up to twelve feet in diameter; if one is extremely fortunate, the hole may be contained within a heated ice house, rather like an ice fisherman’s shack. (Ice divers will also sometimes borrow the air holes of Weddell seals to gain purchase.) Once in the water—which can be as cold as 28 degrees Fahrenheit—you must keep warm. Dry suits are essential, and it’s recommended that visitors log a number of drysuit dives before arriving. You’ll also want attached dry gloves, layers of polypropylene undergarments, and a regulator that’s low-temperature–ready. (Fortunately for researchers, McMurdo Station maintains a well-stocked inventory of cold-water diving accessories.)
Antarctica. Ice Diving. Mcmurdo Sound
“As I prepared for my first dive, I had a mix of fun-anticipation and anxiety—it’s hard not to wonder if you’re going to be able to do it or not,” Linda continued. “It was a bright, sunny day. I dropped down through the ice and looked up. The sunlight was coming through the ice, making it a glacier blue, one of the most beautiful things I’ve ever seen. I was awestruck by how colorful it was. Just talking about it, I get chills. It was a surreal world, as beautiful as any tropical reef.” Properly outfitted, Linda managed to stay comfortable. “A tiny bit of my face was exposed, the area underneath my mask where my hood comes to my chin. But overall, being cold was not a huge problem.”
Crazy Ice Diving
Visibility in the waters under the ice of McMurdo Sound can be astounding. “The water had hardly any suspended particles,” Linda explained. “When you look up, you can see the ice hole very clearly, even from sixty or seventy feet. Some of my fellow researchers have been there in the early spring before there’s been much sun, and hence very little plankton. They say that at that time, visibility can be up to 1,000 feet; one time, they drilled separate holes 1,000 feet apart, and the divers insist they could see each of these exit points.” Visibility of 300 to 600 feet is more common.
The kaleidoscopic refractions of light filtering through McMurdo Sound’s thick ice are not its only attraction. A host of invertebrates awaits. “One of the things that I really like to do is look at small stuff—perhaps because I spend a lot of time looking through a microscope in my work,” Linda continued. “There’s an animal called Glyptonotus antarcticus that’s found in the waters of McMurdo Sound.
In other parts of the world, this type of isopod grows to only a few centimeters. In Antarctica, I saw them up to five or six inches in length. Animals in these constantly freezing cold waters don’t have to spend a lot of energy adjusting to temperature changes, and this helps them grow very large. This is true for sponges, sea stars, and other crustaceans, too. On one dive, when we went down deeper than usual—to 160 or 170 feet—we photographed sponges that were six feet tall!”
Seemingly infinite populations of krill in the waters of Antarctica provide a biomass foundation that supports vast quantities of bird, pinniped, and cetacean life. However, visitors are more likely to come upon seals and penguins on open water or above the ice than below. One local pinniped that divers would do well to avoid is the leopard seal, which frequents pack ice during the more clement months. This predator, identified by its slightly reptilian head and a white throat that’s decorated with black spots, is the only seal that will attack and devour other seals.
LINDA KUHNZ is a senior research technician at the Monterey Bay Aquarium Research Institute, where she studies ecological relationships among small animals that live in the top few inches of marine sediments (infauna), and larger invertebrates and fishes that live on the sea floor or just above it. When she’s not working, she’s often found diving with Abreojos Diving Adventures, a diving club she operates from bases in Monterey, California, and the North Kohala coast of Hawaii.
Are you ready? Antarctic Ice Diving! If You Go:
Getting There: Those not accompanying a research expedition will have to travel to Antarctica by boat, as no commercial air service is available.
Best Time to Visit: Trips to the Antarctic are limited to the spring and summer—roughly November through April.
Accommodations: The number of ships offering dive-oriented expeditions to Antarctica is limited. One operator is Australia-based Aurora Expeditions (+61 29-252-1033; www.auroraexpeditions.com.au).
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