HAVANA - A US veteran swimmer started here on Saturday her fourth attempt to swim across the Straits of Florida, which separates Cuba and the United States, without a protective shark cage.

Endurance swimmer Diana Nyad swims off as she begins a trip across the Florida Straits to the Florida Keys, starting from Havana, Cuba, August 18, 2012. [Photo/Agencies]

If it is done, Diana Nyad, 62, will set the record of the first swimmer to cross the 93-mile (150-km) strait full of sharks from Havana's Marina Hemingway to the Florida Keys.

She was assisted by a 30-member team in yachts and kayaks, including divers and experts in shark attacks.

Nyad said that with her endeavor she aimed not only to establish a personal record but also to make closer the two nations without official relations since 1961 for political differences.

Nyad holds the world record of long-distance swimming at sea since 1979, when she swam 102 miles (164 km) from the island of Bimini, the Bahamas, to Key West in Florida.