Learning how to walk on water (when it's frozen)

Sea ice training and travels at Casey

On this first week of July where we celebrate NAIDOC week, Casey station is enjoying a subtle increase in daylight since our Midwinter celebrations.

Thanks to Flynn, our winter FTO (Field Training Officer) we are all sea ice travel-trained and able to enjoy the delights of this unique environment from a different perspective.

For now we have a blanket of sea ice around us, almost as far as the eye can see, with some massive icebergs way off in the distance.

At Casey the sea ice is not as reliable as it is at Davis and Mawson stations, for a variety of reasons, so travel on the sea ice tends to occur on foot rather than via station vehicles. As such, preparations for a trip means we don our winter boots, microspikes, survival packs and then off we go.

Regular sea ice thickness checks are done through the season by the sea ice monitoring team here at Casey.

Sea ice is a frozen film on the surface of the ocean. It is of uncertain and unpredictable thickness, strength, reliability and permanence due to factors like ocean swell, strong winds, air and ocean temperatures and the condition of the ice.

Under the ice the environment is stable with a temperature of -1.85°C all year, and is a teeming wonderland of sea life: fish, urchins, sea cucumbers, worms and stunningly colourful forests of anemones, sponges and vegetation that make the floor look more like a tropical coral reef rather than a frozen bay at the bottom of the world.

The sea ice is safe for foot travel when it is 20 cm thick. The most reliable way to gauge sea ice thickness is to measure by drilling with a drill or hand auger and using a specially designed measuring tape. When travelling on the sea ice we carry our survival packs, are in constant radio communication with station, and have our reliable ice axes and throw bags at the ready. The ice axe allows us to gauge the thickness of the snow on the surface of the ice and to chip a narrow trench into it with the adze. The throw rope, 15 m long, acts as a lifeline to anyone unfortunate enough to fall through the ice, which of course will not happen!!

It truly is a privilege to meander along over the sea that many of us travelled over by boat during summertime, and to be witness to the ever changing features of this precious place.

-Deirdre McCormack (Dee) - Station Doctor

Six people in robust weatherproof clothing including face coverings, thick gloves and padded jackets, standing on a flat, snow-covered stretch of sea ice. They are all wearing large backpacks and carrying ice axes. One holds a powered drill with a metre-long drill flight attached
Two people in thick winter clothing standing on sea ice. One is using a powered handheld drill to drill into the sea ice, while the other watches on
A person kneeling on a wide plain of sea ice. He is inserting a length of stiff measuring tape into a recently-drilled hole in the ice to measure its thickness
A team of people in thick Carhartt jackets working on a stretch of sea ice. An area a few metres squared has been cleared of snow, and some of the cleared ice has been cut through. A large chunk of ice, 1-2 metres wide and 40-50 centimetres deep, is being lifted with pegs and ropes. Unfrozen water can be seen just below it
Two people in robust weatherproof clothing including insulated jackets, thick gloves and face coverings, kneeling down on a wide stretch of sea ice. They are each holding up an ice axe, brought together to form an 'X' with the axe handles
An Antarctic dawn, featuring pink-tinted clouds above an irregular snowy landscape. The scene in fact comprises of an ocean bay with icebergs and some low hills in the distance, but they are almost indistinguishable from one another beneath unifying coverings of ice and snow
Four people grouped together for a photo, smiling at the camera from behind their neck buffs and balaclavas. They are dressed for very cold weather, also wearing beanies and thick, insulated jackets. A rocky, snow-dusted coastline and sea ice can be seen behind them
An Antarctic sunset scene. Snow-covered rocks in the foreground slope downwards to a wide expanse of pale, ice-covered ocean. A series of icebergs line the distant horizon. The sunset brings out a streak of fiery colour between the thick clouds overhead and the sea ice below
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