Cruising the web I ran across another reason to stay out of the water. Better than six feet long, aggressive, they hunt down and kill, and will eat just about anything:
http://scienceblogs.com/zooillogix/2008/09/giant_antarctic_marine_worm_pa.php

Just about horrid enough to give me nightmares.

The good news is that if your not in the habit of swimming in the frosty cold antarctic seas your not likely to run into one of these critters. Yes, they are big, and gross, and scary ,and potentially aggressive but after looking around a bit more I could find no record of any human ever being killed by one of them.

The point here is that life is provisional. Your always in danger of dying. But the ugly, obvious, scary things are not necessarily the biggest threat. Your far more likely to die in an auto accident than in a hurricane or in a riot. Some day in the future some extremist may set off a dirty bomb that will cause a panic, force the abandonment of a good part of a city and might cause leukemia or cancer in a few people. But in the mean time every day 55 people will die because of a slip or fall.

There are many really scary things out there that might hurt you or your family. When preparing for risks you have to rate them in terms of probability. If you feel the need to get a gas mask I wouldn't want to dissuade you from doing so. But make sure you have a bath mat laid down in the tub.

A big worm is scary and worrying about dirty bombs is fashionable and sexy in some circles but don't let this distract you from protecting yourself and your family from the more probable, but much less glamorous, threats.

*laughs*

I know where there is an entire icy lake. I wonder if they can survive freshwater and will eat lamprey.

Oh, wait, never mind. Add a bio weapon to get rid of the lamprey, then we need to get rid of these.

I think about it this way.....it is kind of like my watch being 'waterproof to 660 ft......if I am at 660 feet....I have more to worry about than my watch being waterproof.....

If I'm every in the water in the antarctic.....I have more to worry about than these things.......LOL

I already have enough reason to stay out of the water. Once you enter the ocean, you have surrendered your position at the top of the food chain.