MIAMI - Endurance athlete Diana Nyad has decided to end her swimming ultramarathon from Cuba to Florida about halfway through, as her face and body grew swollen from painful man o' war stings.

Medics warned another sting could be life-threatening.

Nyad team member Vanessa Linsley said the swimmer was disappointed and emotional.

The 62-year-old swimmer has completed at least 49 miles (79 kilometers) of the 103-mile (166-kilometer) passage of the treacherous Florida Straits.

Nyad tried last month, but had to quit after a serious asthma attack made it difficult to breathe.