KEY WEST, Fla. — A 49-year-old grandmother and veteran endurance swimmer scuttled her quest early Sunday 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 a more than 100-mile ocean odyssey.

Penny Palfrey had fended off painful jellyfish stings while keeping an eye on hammerhead sharks as she attempted the crossing without a shark cage.

But her support team said the tricky currents of the Florida Straits proved to be her biggest obstacle, pushing her east so that she ended up losing ground just as she was achingly close to her goal, said her husband, Chris Palfrey.

All told, the British-born Australian athlete had been swimming nearly 41 hours since plunging into balmy waters near Havana, Cuba, on Friday to start out. She was about three-quarters of the way into her swim when she gave up the effort about midnight, just 26 miles south of Florida’s Key West.

Palfrey treaded water as the crew briefed her on the currents, and she ultimately made the decision to end the swim.

“Penny has been 100 percent focused on this swim for a year, so she was quite a bit upset,” her husband said at a Key West news conference.

She was hospitalized Sunday, receiving IV drips and pain medication. Blisters and ulcers under her tongue made it difficult to talk. Her husband said it was too early to discuss the possibility of another attempt.

Her doctor said she was dehydrated and had low blood pressure.