Nyad has always excelled in the water. Fifteen minutes into her first swim practice — fifth grade, Fort Lauderdale, Fla. — the coach leaned toward the pool and said, “Kid, you’re going to be the best swimmer in the world.” Nyad hurled herself at the sport, four hours a day, six hours a day. “All kids love doing what they’re good at, and I’m just this ridiculous Type A personality. I used to never go to the bathroom to pee without having vocabulary cards.” Swim practice also removed Nyad from her house, enabling her to avoid her father (actually, her stepfather, though Nyad didn’t know that as a child), a mercurial figure who read Nyad “The Odyssey” and woke her at 3 a.m. to see a full moon, but who could also make family life unpleasant. “In the water I felt safe,” Nyad told me. There, she was also protected from the sexual abuse she says she experienced in her high school years. “I was 14 all the way through 17. I was stronger than I am now, and I didn’t stop it. I didn’t slap him or throw him against the wall or go . . . to my mother.”

To cope with the pain, Nyad became obsessed with survival stories: those of polar explorers Roald Amundsen and Robert F. Scott, along with David Howarth’s “We Die Alone,” the story of a Norwegian man crushed by an avalanche who spent days buried under several feet of snow and who cut off his own frostbitten toes to avoid gangrene. As Nyad writes in her 1978 memoir “Other Shores,” she sought to learn from these epics how “to dig deeper and deeper into your gut until you arrive at that same core of pride and dignity that the survivors know.” Nyad chose the water as her medium. “At 16,” she writes, “I was not the best in the world, but I was damn good.”

At 60, Nyad wanted to feel damn good again. “People ask: ‘What’s in it for you? Is it all masochism? Is it just that it feels bad and then good to be done?’ No,” Nyad says. “When I’m out there, I’m thinking to myself: I’m a rare breed. There aren’t many people in the world who can do this.”

By early last summer, Nyad had whipped herself into what she called “monstrous shape.” Fifty people accompanied Nyad in her August attempt to swim from Cuba to Florida, filling three boats. But Nyad’s crossing of the Straits of Florida didn’t go as planned. After blowing a bugle at the Havana harbor and jumping into the water, Nyad had to abort her swim after 51 miles and 28 hours because of a 12-hour-long asthma attack (the first she ever suffered while swimming). She tried again in September, but with worse luck. Just two hours in, several box jellyfish stung Nyad, forcing her to tread water for two hours while she received medical care. She then resumed swimming and progressed for about 24 hours — until the box jellyfish stung again. This time Nyad left the water, spending four hours receiving oxygen, painkillers, epinephrine and prednisone on the boat. Still, once again, Nyad returned to the ocean. But 41 hours and 90 miles after leaving Havana, Nyad was informed by handlers that reaching Florida was impossible. Her stings had slowed her stroke rate from 60 to less than 55 per minute. She could no longer make headway toward land against the current.

“I think I’m going to my grave without swimming from Cuba to Florida,” she told CNN.

Back home, at the end of September, Nyad threw away all her swimming gear. But she did this on Monday; her garbage is collected on Fridays. Thursday she fished from the cans her suits, caps and goggles. The will to swim from Cuba to Florida had returned.

“It’s a big megillah, this swim,” Nyad says, back at home, shoving her two dogs off a couch in her house in the Hancock Park neighborhood of Los Angeles. In addition to training for yet another year, Nyad needs to raise $300,000 through motivational speeches and sponsorships; woo back her support team; secure visas, boats and shark wranglers; and, most pressing, learn how to protect herself from jellyfish stings. The jellyfish that halted her last Cuba effort carries a neurotoxin, like a snake’s venom, which it delivers through tens of thousands of tiny harpoons on its tentacles. One sting temporarily stopped Nyad’s breathing and paralyzed her back. The question on Nyad’s mind now is whether a skintight suit could protect her. She fetched from her dining room a stretchy blue Lycra unitard, with long legs and long sleeves. The hope, she said, is to find something similar with a jellyfish-proof weave. Once that’s located, Nyad says, she’ll move on to beta testing. Steven Munatones — the unofficial American dean of open-water swimming — “is going to put it on and get in the jellyfish tank at the Monterey Aquarium. It’s going to be amazing.”