Travel
If staying put on Antarctic sea ice is fraught with peril,
traveling across it is even more so. For not only are your
chances of suffering frostbite or getting lost in a whiteout
or dying from hypothermia even greater, but you also have to
cope with extremely treacherous ice conditions. As the
Shackleton
expedition's forays over the Weddell Sea ice showed, traveling
over pressure ridges - places where colliding floes have
tossed up massive slabs of sea ice - is challenging if not
impossible. In addition, cracks can appear without warning,
weak bridges of ice can form over unseen leads, and sea ice
begins to break apart when the seawater temperature rises
above 28.5°F or even in strong wind or swells.
Seawater immediately beneath sea ice is roughly the same
temperature as the ice, or about 28.5°F. If you fall in,
at the least you may have your breath knocked out of you, or
you may involuntarily lurch into a spastic fetal position and
lose control of your muscles. If unprotected by survival gear,
you would be able to swim at most a mile before the coldness
utterly incapacitated you. If you stayed put where you fell
in, you'd lose consciousness in five to seven minutes and, if
you didn't drown right away, you'd freeze to death in ten to
30 minutes.
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