US swimmer Diana Nyad said this will be her final attempt at making the 103-mile journey from Cuba to Florida without a shark cage.
Ms Nyad said before beginning the gruelling swim, "I'm learning as I get older, and I'm really getting older now, that there's a fine line between having grace and letting go of something that you have no control over and you're just not going to beat, like Mother Nature maybe."
More top news
Hundreds of people have been forced to evacuate their homes in northern California as wildfires ripped through dry brush and scrub oak.
A year-long US-led bombing campaign against Islamic State has left the group no weaker, American intelligence agencies have said.
Wembley Stadium hosts the women's FA Cup final for the first time this weekend when last season's beaten semi-finalists meet