U.S. swimmer Nyad plays a trumpet before attempting to swim to Florida from Havana.
U.S. swimmer Nyad plays a trumpet before attempting to swim to Florida from Havana.The 61-year-old plunged into the Straits of Florida at dusk on Sunday to begin what she hopes will be a world record 103-mile (168 km) swim from Cuba to Florida. The same swim was completed successfully by Australian Susan Maroney in May 1997. But Nyad's claim to a world record will be that unlike Maroney, she is doing it without a shark cage in the strait's warm, shark-infested waters. Nyad will be protected by a surrounding electrical field and by divers who will watch for sharks and drive them away if they get too close. REUTERS

Diana Nyad, 61-years-old, is "still going strong 22.5 hours" into her historic swim from Cuba to Florida, tweeted CNN's Matt Sloane, who is in a boat accompanying the swim.

However, the wind was picking up into the evening and the rough seas were slowing Nyad and the boats. Moreover, she is experiencing some shoulders pains and suffering from "a little touch of asthma," tweeted Sloane.

Nyad's swim, scheduled for 60 hours and stretching for 103 miles, began at 7 p.m. ET on Aug. 7 at Marina Hemingway in Havana, Cuba.

The Cuba-Florida swim has been done before (in 1997). However, Nyad's feat would still be a first because she's doing it without a shark cage. Rather, she has only an electrical frequency shark shield and divers to keep the sharks away.

Nyad isn't just after a record, however. She's also proving a point about age.

She tried the same feat in 1978 at the age of 28, but quit 42 hours into the swim. Now, 33 years later (and older), she's looking to best the younger version of herself.

"I'm almost 62 years old.... I'm standing here at the prime of my life; I think this is the prime, when one reaches this age. You still have a body that's strong, but now you have a better mind," she said to reporters before the swim, reported LA Times.

Cuba Florida