American marathon swimmer Diana Nyad ended her second bid to swim from Cuba to the Florida Keys about halfway through her journey early Tuesday.
Elaine Lafferty, who was on the boat according to Nyad's blog, posted on Twitter: "It's over." Lafferty said "the combination of factors was too much to safely continue."
According to the Twitter feed, Nyad was pulled from the water early in the morning after swimming for 29 hours. The swim was expected to take 60 hours to cover at least 166 kilometres.
The Twitter account reported she decided to end the swim herself, after "realizing the conditions of 5 to 10 knot winds and less than ideal currents."
An online chart plotting the swim's track showed the Gulf Stream currents pushing Nyad to the east of the intended course. Nyad had hoped to end her swim at the Southernmost Point in Key West.
According to the Twitter feed, Nyad was on a support boat after ending the swim and wrapped in blankets.
In her second attempt, Nyad tried to accomplish at 61 years old what she failed to do at 28 in 1978. This time, she even attempted the swim without a shark cage, relying instead on an electrical field from equipment towed by kayakers to keep them at bay.
In her first attempt in 1978, she quit after being in the water for 41 hours and 49 minutes due to strong currents and rough weather that banged her around in the shark cage.
Had the latest attempt been successful, Nyad would have broken her own record of 165 kilometres for a cageless, open-sea swim, set in 1979 when she stroked from the Bahamas to Florida.
Before the swim, Nyad told journalists she hopes her swim will inspire others her age to live active lives. She said she also hopes it can help improve understanding between Cold War rivals Cuba and the United States, even if just symbolically.