By MATT SEDENSKY, Associated Press

KEY WEST, Fla. -- Endurance swimmer Diana Nyad has ended her fourth bid to swim from Cuba to Florida after four days of storms, jellyfish stings and shark threats.

Nyad's support team posted on her blog that the athlete made the call after being pulled from the water a day before her 63rd birthday.

Nyad left Havana on Saturday in her third attempt since last year to be the first person to swim the Florida Straits without a shark cage. She also failed once earlier to do so with a cage.

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  • Diana Nyad

    Endurance swimmer Diana Nyad rests after being pulled out of the water between Cuba and the Florida Keys early Tuesday, Aug. 21, 2012. (AP Photo/Diana Nyad via the Florida Keys News Bureau, Christi Barli)

  • Diana Nyad

    Endurance swimmer Diana Nyad rests after she was pulled out of the water between Cuba and the Florida Keys early Tuesday, Aug. 21, 2012. (AP Photo/Diana Nyad via the Florida Keys News Bureau, Christi Barli)

  • Diana Nyad

    Endurance swimmer Diana Nyad is aided after she was pulled out of the water between Cuba and the Florida Keys early Tuesday, Aug. 21, 2012. (AP Photo/Diana Nyad via the Florida Keys News Bureau, Christi Barli)

  • Diana Nyad

    This Aug. 18, 2012, file photo shows Diana Nyad adjusting her swimming cap as a woman applies a protective ointment to her skin before she prepares to jump into the water to start her swim to Florida from Havana, Cuba. (AP Photo/Ramon Espinosa, File)

  • Diana Nyad

    In this photo endurance swimmer Diana Nyad swims in the Florida Straits between Cuba and the Florida Keys Monday, Aug. 20, 2012. (AP Photo/Diana Nyad via the Florida Keys News Bureau, Christi Barli)

  • Diana Nyad

    Endurance swimmer Diana Nyad is hydrated by a crew member in the Florida Straits between Cuba and the Florida Keys Monday, Aug. 20, 2012. (AP Photo/Diana Nyad via the Florida Keys News Bureau, Christi Barli)

  • Diana Nyad

    People from the local nautical club carry a Cuban and a U.S. flag to the coast to watch U.S. swimmer Diana Nyad start her swim to Florida from Havana, Cuba, Saturday, Aug. 18, 2012. (AP Photo/Ramon Espinosa)

  • Diana Nyad

    Diana Nyad takes a break after reportedly being stung by a jellyfish Saturday, Aug. 18, 2012, off Havana, Cuba. Nyad, who turns 63 Aug. 22, is trying to be the first swimmer to cross the Florida Straits without a shark cage. (AP Photo/Diana Nyad via the Florida Keys News Bureau, Christi Barli)

  • Diana Nyad

    Endurance swimmer Diana Nyad (yellow bathing cap) pauses for a rest and hydration with her support crew in the Florida Straits between Cuba and the Florida Keys, Sunday, Aug. 19, 2012. (AP Photo/Diana Nyad via the Florida Keys News Bureau, Christi Barli)