It's been called the Holy Grail of marathon swimming and it starts here, a marina in Havana where swimmers have tried - but failed - to set off unassisted from Cuba to the U.S.<br/> <br />On Wednesday, 28-year-old Australian Chloe McCardel took a shot at the grail, by trying to become the first person to make the swim WITHOUT a protective shark cage, which helps cut through the water.<br/> <br />REPORTER OFF CAMERA: "How are you feeling?<br/> <br />MCCARDEL: "Very well, thank you.<br/> <br />The sea looks calm now, but difficult currents stymied earlier efforts by others.<br/> <br />This time, the swimmer has lots of help - an army of 50 to help her navigate, and an underwater electromagnetic field to repel sharks.<br/> <br />McCardel is making the swim for cancer research and to improve U.S.-Cuban relations.<br/> <br />If all goes well, she'll reach Key West in about 60 hours on Friday night.
