Diana Nyad calls the quest the `` Xtreme Dream '' of a lifetime''. Nyad will begin the swim in Cuba on Sunday . She holds the world 's record for the longest swim .
Diana Nyad calls the quest the `` Xtreme Dream '' `` This has got to be the last time , '' she says . Nyad will begin the swim in Cuba on Sunday . She holds the world 's record for the longest swim .