They say no Alcatraz prisoner ever swam his way to freedom because the water in the San Francisco Bay is so treacherous. The story, however, says nothing about lawyers.

Maybe that's why Walter Bunt Jr., a partner at the firm of K&L Gates, is more excited than apprehensive as he trains for the 1 1/4-mile swim from Alcatraz Island to Aquatic Park. He'll be traversing the waters on Sunday with his son, Jonathon, who challenged his father to make the swim with him.

The Bunt men, ages 61 and 29, are practiced swimmers whose idea of paradise is cutting through a wide stretch of open water. They will be joining 10 others on their adventure under the auspices of Swim Art, a San Francisco outfitter that organizes a variety of athletic events in the bay. As the participants match their strokes against the currents, a Swim Art boat will trail along with rescue equipment and medical supplies, just in case.

Among his friends, Mr. Bunt said with a laugh, "The vote is running 10-to-1 that I need psychiatric help."

But his wife, Nancy Bunt, said she's delighted that her husband and son will be doing this together. Mrs. Bunt will be in the escort boat, as will her son's fiance, Andrea Nadosy.

"It's not a long swim," said Mr. Bunt, who expects to be in the water an hour or less. "The real issue is the current and the chop."

And the temperature. The bay tends to be at its warmest in late September, but that's still only 57 to 60 degrees. Mr. Bunt will be wearing a wet suit, but his son will not.

"I've been conditioning myself to swim in the bay without one," said Jon Bunt, a triathlon competitor who moved to San Francisco two years ago to start his own business. He said he swims in the bay at least once a week all year round but has never done it from Alcatraz, and that he's upped the frequency of swims in preparation for the date with his dad.

Mr. Bunt, a former runner, switched to swimming when his knees gave out. He is training for the big day with extended sessions at the Downtown YMCA pool and outdoor swims whenever he can get to the water. He's also been riding his bike and lifting weights.

"I've swum with Jon in the San Francisco Bay, but never like this," he said.

"When I first moved here I didn't think it was possible [to swim to shore from Alcatraz]," Jon Bunt said. "You always hear that no prisoner is known to have escaped because the water was so cold. But there are a lot of people in the outdoors subculture here who do it."

Leslie Thomas, owner of Swim Art, said five big races a year take the same route, involving thousands of contestants. She also runs seven groups a season from Alcatraz with an average of 20 people each. Her oldest client was 72, and her youngest a teenager. The youngest ever to complete the swim was a 9-year-old from Arizona, she said, while the oldest are swim club members in their 80s who eschew wet suits.

"For a lot of people who do it, it's a pretty big deal," Ms. Thomas said. "They set it as a goal and train for it. In a lot of cases it's the farthest, coldest, roughest water they've ever swum, so it's a big accomplishment."

But, she stressed, "It's extremely dangerous to do it without the proper escort coverage. It's also required by the U.S. Coast Guard that we register the swims with them."

Contrary to popular lore, she said, sharks are not a problem.

"There are five species of sharks in the bay but they're all bottom dwellers and even under the most extreme conditions not interested in eating a human being," she said. "The great white sharks off the coast have never been sighted in the bay."

Alcatraz Island has been a national recreation area since 1972. From 1934 to 1963 it housed a federal prison nicknamed "The Rock." Its inmates included George "Machine Gun" Kelly, Al Capone and Robert Stroud -- "The Bird Man of Alcatraz" -- as well as Frank Morris, John Anglin and Clarence Anglin, whose escape in 1962 was the basis of the movie, "Escape from Alcatraz," starring Clint Eastwood.

Given that those three escapees, and a few others, were never found, and all were classified "presumed dead" by the authorities, does Ms. Thomas believe that none of them survived the bay and kept on going?

"If I had to guess, I'd think someone made it," she said. "It's really not that far, and if those guys were studying the tides I'm sure they had a sense of what to do. The tough part would have been the direction of the current and knowing how to swim across the current.

"Of course, the prisoners weren't doing a heck of a lot of exercising or eating the most healthy food, so they wouldn't have been very fit."

The Bunts on the other hand, are working hard to be as fit as possible on the big day. They will be making their swim very early in the morning, when there's not much ferry traffic in the bay, and ending up on the beach below Ghirardelli Square -- a convenient place for replenishing one's depleted energy with high-test chocolate.

"It's great to see them doing this together," said Nancy Bunt. "San Francisco is such a gorgeous city. If you're going to do something as crazy as this, what better place?"