Man wears speedo during an Outdoor Swimming Club's December Dip

Photo: Ben A. Pruchnie/Getty Images

Polar bear plunge

A hefty man wearing a Speedo and a skimpy "mankini" prepares for the start of the annual 'December Dip' on Dec. 7 in Parliament Hill, London, England.

Organized by the Outdoor Swimming Society, the chilly event attracts hoards of daring people in quirky costumes looking for an invigorating winter workout.

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Outdoor Swimming Club in London participates in December Dip

Photo: Ben A. Pruchnie/Getty Images

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Catie Leary is a photo editor at Mother Nature Network. Follow her on Twitter and Google+.