Endurance swimmer Penny Palfrey, who is 49, ended her attempt early Sunday (1) to become the first woman to swim unaided from Cuba to the Florida Keys, unable to close the gap on the last 26 miles of the 103 miles span of water.

She was about three-quarters of the way into her swim when she gave up the effort about midnight, just 27 miles south of Florida’s Key West. Palfrey was trying to be the first person to swim the Florida straits without any assistance: no shark cage, flippers, wet suit or snorkel.

Her crew tweeted few details early Sunday of the end of her quest but said: “Penny Palfrey had to be pulled out of the water … due to a strong southeast current that made it impossible for her to continue her swim. Penny is presently on her escort boat being taken care of by her crew.”

“She is fine,” Andrea Woodburn, one of the team members, confirmed by telephone from Key West according to Associated Press.

Two yachts, a kayak and a boat were part of Palfrey’s support team. The vessels carried ultrasound equipment to ward off sharks.

She currently holds the record for the longest unassisted swim of 67 miles from Little Cayman to Grand Cayman she did last year.

Last year, swimmer Diana Nyad twice tried to make the swim also unassisted but was turned back by health problems and stinging jellyfish.

Palfrey estimated the trip would take her between 40 and 60 hours.

By making it this far, Palfrey has already broken her own world record of the longest unassisted ocean swim of 59.64 nautical miles (110.45 kilometres), her team members said.

Despite her failure, her Facebook page quickly filled with comments by well-wishers, expressing support and saying that making it so far was already a great achievement.

Palfrey began swimming at the age of nine.