Havana, Cuba (CNN) -- Endurance swimmer Diana Nyad's latest attempt to swim across the Straits of Florida ended Tuesday morning after severe jellyfish stings and a lightning storm put her off course, her team said.
She had been in the water for 60 hours and was about halfway (almost 50 miles) through her swim from Cuba to Florida.
Nyad was stung by jellyfish overnight, and a major lightning storm put anyone in the water in extreme danger, said Mark Sollinger, Nyad's operations chief. He said the 62-year-old exhausted swimmer was pulled out as the dangers mounted.
"With all the threats continuing, Diana decided that it was not a risk that we wanted to take," Sollinger said.
Nyad's lips and face are swollen, but she is holding up "as well as someone who just spent 63 hours" performing a "monumental and extremely dangerous" feat, Sollinger told CNN's "Starting Point with Soledad O'Brien."
Sollinger described her achievement as "huge," despite having to stop before she reached Florida.
"It's a cross between being down, being so tired because everyone wanted this so much, and a huge sense of accomplishment," he said. "Nobody in the world would even attempt this, but we did."
Nyad was making her fourth attempt to swim across the Straits of Florida. The full distance from Havana, Cuba, to Key West, Florida, is 103 miles.
On Saturday night, her first night in the water, Nyad was stung by jellyfish on her lips, forehead, hands and neck, her blog said.
The next night, a sudden squall blew her off course.
"There is lots of lightning out there and the storm is blowing right on top of Diana," a blog post stated early Monday, adding that the swimmer was safe and "feeling strong."
But Nyad and her crew were treated to a grand display of dolphins Monday evening.
Nyad's first attempt to cross the Straits of Florida was in 1978, when rough seas left her battered, delirious and less than halfway toward her goal.
She tried again twice last year, but her efforts ended after an 11-hour asthma attack and jellyfish stings.
Nyad insisted Friday she was ready to try it again. "I'm feeling tremendous inner pressure that this has got to be it, this has got to be the last time," she said.
Nyad was swimming without a shark cage, relying on electronic shark repellent and a team of divers to keep the predators away.
In the 1970s, she won multiple swimming marathons and was one of the first women to swim around the island of Manhattan. She holds the world's record for longest ocean swim -- 102.5 miles from Bimini in the Bahamas to Jupiter, Florida.
Nyad said she was 8 years old when she first dreamed about swimming across the Straits of Florida. At the time, she was in Cuba on a trip from her home in Florida in the 1950s, before Fidel Castro led a Communist takeover in Cuba and the country's relations with the United States soured.
"I used to stand on the beach and I said to my mother, 'I wonder if anybody could swim over there,'" Nyad recalled saying while pointing to the Keys.
In her 60s, she says, she still feels "vital (and) powerful" -- and definitely "not old." A successful swim ideally will inspire people her age and older not to let their age hinder them, Nyad said.
"When I walk up on that shore in Florida, I want millions of those AARP sisters and brothers to look at me and say, 'I'm going to go write that novel I thought it was too late to do. I'm going to go work in Africa on that farm that those people need help at. I'm going to adopt a child. It's not too late, I can still live my dreams,' " she had said.