In this photo provided by Diana Nyad, via the Florida Keys News Bureau, Diana Nyad takes a break after reportedly being stung by a jellyfish Saturday, Aug. 18, 2012, off Havana, Cuba. Nyad, who turns 63 Aug. 22, is trying to be the first swimmer to cross the Florida Straits without a shark cage. (AP Photo/Diana Nyad via the Florida Keys News Bureau, Christi Barli)

PETER ORSI

HAVANA (AP) - Team members for Diana Nyad report the 62-year-old endurance athlete has been stung four times by jellyfish while continuing her quest to swim from Cuba to Florida in shark-infested waters.

A team member posted a message on Nyad's Twitter account that the American had logged more than 10 hours in the water by nearly 2 a.m. EDT Sunday. Her goal: to become the first to set a record 103-mile (166-kilometer) unassisted crossing without a wetsuit or shark cage.

Nyad was stung on the lips in the second of the four encounters with jellyfish but kept swimming, her team says. She left Cuba Saturday in her latest bid to cross the Florida Straits since last summer, when first an asthma attack and then jellyfish stings forced her to abandon separate attempts.

HAVANA (AP) - Less than a week shy of her 63rd birthday, American endurance athlete Diana Nyad is trying for the third time in a year to become the first person to swim across the waters separating the U.S. from Cuba without using a shark cage.

Nyad was stroking steadily through the Straits of Florida early Sunday in a quest to set a record 103-mile (166-kilometer), unassisted crossing without a wetsuit or protective shark cage.

Australian Susie Maroney used a cage when she swam across the Straits of Florida in 1997.

Just before jumping into the water off a Havana jetty Saturday afternoon, Nyad spoke of how the monotony and sensory deprivation of marathon swimming is most intense at night, leading the mind down contemplative paths.

"I do enjoy, when I stop in the middle of the night and I see the stars, you start thinking out there," she said. "It becomes very metaphysical. ... You're tired and you've been having this metronomic stroke taking you into a different world, all of a sudden you're out there and you're thinking about the meaning of life and the grandeur of the universe and the mystery of it all."

There will be less time for introspective breaks this trip, however, as shifting forecasts showed Nyad's window of flat, calm seas threatening to slam shut a day earlier than expected.

That forced the go-time to be moved up nearly 15 hours to Saturday afternoon instead of around dawn Sunday, a time that had been chosen to minimize Nyad's exposure to jellyfish that tend to surface more at night.

A member of Nyad's team posted a message on her Twitter account late Saturday saying the swimmer had been stung by a Flower Hat jellyfish - not the more dangerous box jellyfish that ended one of her attempts last year. One of her shark divers also was stung. Both were said to be OK.

Friend and trainer Bonnie Stoll said the narrowing window was not insurmountable, and they still hoped to arrive in the Florida Keys sometime Tuesday.

They'll try to win a minute here, a minute there, by shaving time off Nyad's scheduled stops for rest and nutrition.

"I don't care about the time. I just want to make it there," Nyad said.

This is her third try at taming the Florida Straits since last summer, when first an asthma attack and then jellyfish stings forced her to call off separate attempts.

This time Nyad had hoped a custom-made swimsuit would protect her from stings. It covers her head-to-toe with a pantyhose face and holes only for the eyes, nose and mouth.

A kayak-borne apparatus shadowing her in the water creates a faint electric field designed to repel most sharks, and a team of handlers was on alert to dive in and gently nudge away any that make it through.

Deeply tanned with freckles and goggle-eyes from long hours training in the sun, Nyad admitted to a minor case of nerves but said she was confident despite the last-minute change in plans.

"I feel really excited," she said. "I respect this. I know how difficult it is. There's a reason no-one's ever done it, but I'm prepared. ... I may suffer some, but I'm prepared for that, too."

Nyad has been training for this for three years, and Stoll said she had a good 24-hour practice swim last week.

"We are in peak shape," Stoll said.

Nyad's team expected it would take at least 60 hours to complete the swim to the Keys.

In June, Australian endurance swimmer Penny Palfrey made it 79 miles toward Florida before throwing in the towel in the face of strong currents.

A fiercely driven competitor, Nyad acknowledged it was hard to watch Palfrey come close to snatching away her long-held goal.

"If she had succeeded I would have congratulated her, because I know how difficult it is, more than anybody. And after all, this is not my ocean," Nyad said. "But it is my dream. ... Frankly - how can I lie? - I'm glad that I still have the chance to be first."

Nyad also tried to swim the straits as a 28-year-old in 1978 with the aid of a shark cage, but fell short.

Speaking with reporters Saturday, Nyad would not rule out another attempt should this one fail, but she seemed to acknowledge that even she has a limit.

"This Cuba swim obsession of mine, dating back to 1978 ... is at the last horizon," she wrote in an essay published on the Huffington Post.