=http://boards.straightdope.com/sdmb/showthread.php?t=291845]This thread mentions swimming/thrashing humans. I wonder, what mode of swimming is least likely to attract sharks? I’m guessing something like the breast stroke or the doggy paddle.
Well, i guess it’s reasonable to assume that the more you thrash about, the more likely a shark is to notice you. I remember reading once in a book on sharks that they tend to be especially attracted to the lighter-colored parts of the body, like the palms of the hands and the soles of the feet which, coincidentally, are also the bits that thrash around the most.
The Florida Museum of Natural History’s Icthyology Department has a fantastic section of its website devoted to Sharks, and it also maintains worldwide data on shark attacks in its International Shark Attack File.
The statistics page shows that, since the 1980s, surfers are far more likely than swimmers to be attacked by sharks. This is probably not just a product of their activity in the water, however, but also due to the fact that surfers often surf at remote, unprotected beaches in waters that harbour larger and more aggressive sharks.
Here’s a list of suggestions for bathers looking to reduce the risk of shark attack. Noticce that there’s no advice about swimming style, although it does say to “refrain from excess splashing,” and suggests that you don’t wear shiny jewelry.
Finally, if you’re at all worried about being attacked, this page might allay your fears somewhat.
From mhendo’s cite
Well, I guess that kiboshes the doggy paddle.
I saw something (can’t remember what now) that Great White Shark attacks on surfers may be a case of mistaken identity. One of the Great White Shark’s favorite meals are Sea Lions. From below a surfer paddling on his/her surf board has a silhouette remarkably similar to a Sea Lion (surf board makes a pointy front end with more blunt back end and extended arms to paddle resemble flippers…with the sun shining down all you really see is the silhouette and the resemblance is fairly close). This notion is further bolstered due to many Great White Sharks breaking off the attack after it is begun. The shark generally does not drag the surfer away and eat them but usually strikes and perhaps strikes a second time before giving up when it could easily take the surfer for its next meal. This suggests the sharl itself is surprised by what it actually got (expecting sea lion) and spits it out. Unfortunately the strike from a shark, even one that lays off, is pretty devastating so it may be small comfort to the surfer.
As for best stroke I am led to understand that sharks respond to things in distress. Erratic movements such as that from a paniced person or injured fish tell the shark an easy meal is at hand (much as any predator tends to go for the young, old or wounded…easier meal). A consistent breast stroke or freestyle is probably fine as much as any stroke can be said to be “safe” near man-eating sharks. A calm tread of water might be fine too. Of course there is always the dead man’s float which is more floating than swimming and while you won’t get anywhere neither are you thrashing water very much.
And keep in mind that if they don’t get you in the water, some have a tendency to trying to fool you into opening your door late at night, with a bogus claim of pizza delivery or some such. :eek: 
That was a really funny series of skits. Good ol’ SNL.
Peace,
mangeorge
This source contradicts that as an old myth:
Even if you remain perfectly still in the water, we can still smell you from a hundred meters away.