An Australian endurance athlete has started an attempt to achieve a world-record (roughly 80-mile) swim in the open waters of the Bahamas.

Chloe McCardel started her solo swim Monday morning from Eleuthera island. She hopes to finish some 48 hours later in Nassau, the capital of the sprawling archipelago off Florida's east coast.

The 29-year-old athlete from Melbourne is making the attempt under Marathon Swimmers Federation rules, which means she can't intentionally touch her support boat or hold on to anything.

McCardel last year gave up her quest to swim from Cuba to Florida because of painful jellyfish stings. She went about 11 hours and 14 miles into the 110-mile journey in the Florida Straits before abandoning the attempt.