American long-distance swimmer Diana Nyad had passed the three-quarter mark on her swim across the Florida Straits on Monday, attempting to become the first person to swim from Cuba without a shark cage.
Nyad, 64, was "swimming strongly" more than 39 hours after she set off from Havana, according to blog updates on her website (www.diananyad.com). She had swum more than 80 miles of the 103 miles to the Florida Keys.
The marathon swimmer is making her fifth and final attempt at the crossing, this time using a protective silicone mask to better protect her from the poisonous jellyfish that forced her to end one of two attempted crossings last year.
Nyad said at the outset that the custom-made mask slows her and makes it more difficult to breath. Officials initially estimated it could take up to three days to complete the swim, but Nyad was benefitting from a favorable current, her crew members said.
The treacherous Florida Straits has been conquered only once, by Australian Susie Maroney, who used a protective cage at age 22 during a 1997 swim. The cage glided on ocean currents and enabled Maroney to make the journey in just 25 hours.
Australian endurance swimmer Chloe McCardel abandoned her quest in June to make the crossing after she was severely stung by a jellyfish 11 hours into her attempt.
Nyad departed on Saturday morning accompanied by five support boats that also provide her with food and water.
John Bartlett, a member of Nyad's crew, wrote on her website on Sunday that she had swum farther than on any previous attempt. Her swimming speed had reached 2 mph, he said, "increasing progressively throughout the day."
As night fell on Sunday, Nyad put on a jellyfish-protection suit, the website said. She did not immediately use her protective mask. Instead, the exposed parts of her face were slathered with a special protective cream dubbed "Sting Stopper," it said.
An isolated thunderstorm was reported in the area where Nyad was swimming. Crew member Candace Hogan wrote that Nyad was approaching shallower waters "which could spell danger from jellyfish."
"We can almost see the glow of Key West," Hogan added.
At one point on Sunday, the website said, Nyad floated on her back kicking and led a crew of 35 people keeping her on course through the strong Gulf Stream current in singing "Happy Birthday" to a crew member.
"Diana is feeling strong and very coherent," an earlier update read. "She is joking for the first time all day. The only concern is that she is throwing up everything she eats."
Earlier Sunday, Nyad was stopping every 40 minutes to eat, taking several bites of scrambled eggs and pasta, the blog said.
Her long-distance accomplishments include swimming around the island of Manhattan in 1975 and a swim from the Bahamas to Florida in 1979.