Australian ends Cuba-US swim after jellyfish sting

An Australian endurance athlete has ended her bid to become the first person to swim from Cuba to the US without a protective shark cage, after being stung by a jellyfish.

Chloe McCardel suffered the "debilitating" severe sting approximately 11 hours after she started her record attempt from Havana.

Chloe McCardel during a practice swim ahead of her challenge.

The 28-year-old had anticipated that it would take about 60 hours to arrive in the Florida Keys and spoke of the upcoming challenges at a press conference on Tuesday:

"It is the hardest swim in the world today. No one has been able to achieve this. It’s possibly harder than winning the World Cup or getting a gold medal.”

A message on her Facebook page thanked well-wishers for their support and said that McCardel and her team are now on their way towards Key West in the US.