It's become a New Year's Day tradition, but it's not for the faint of heart.
Dozens of swimmers braved the cold temperatures of the bay in the annual Polar Bear Swim on Sunday morning in San Francisco's Aquatic Park. The event is co-sponsored by the Dolphin Club and the South End Rowing Club.
The tradition dates back to the 1930s, but organizers say that back then it might have served a purpose other than just a brisk swim.
"Originally, they used it as a hangover cure, when they used to just jump off a ferry boat and swim back," said Bill Wygant, president of the South End Rowing Club. "Now it's more of a well-planned event."
Wygant said a combined 93 swimmers from the two clubs participated in the event Sunday. He said the water temperature in the bay was about 50 degrees, with light currents.
"It was really an optimum day for something like this," Wygant said. "Kind of a way for everybody to bring in the new year."