CNN will follow the champion long-distance U.S. swimmer as she takes on the shark-infested waters toward Florida.
Nyad announced Sunday morning at a Havana news conference that she planned to enter the water at Havana's Marina Hemingway to begin her attempt.
"We're going to get started tonight," she told CNN early Sunday morning as she stepped out of a car on her way to the news conference. "As you can probably tell, I'm pretty nervous. My adrenaline is flowing, but I've been training for two years."
Nyad went on to say, "All my life, I dreamed of being the first one ever to swim across without a shark cage," adding that when she turned 60, she "started thinking what if I went back and started to chase that elusive dream of Cuba."
Watch video below uploaded by Nyad!