Leonardo DiCaprio's heroic act that helped save a man's life

Leonardo DiCaprio reportedly helped save a man's life. Photo / AP

Leonardo DiCaprio helped rescue a man who got lost at sea.

The Titanic actor was on vacation on a boat in St. Barts with his girlfriend, Camila Morrone, on December 30 when he heard via a mayday call that a man had fallen overboard from another ship so agreed his vessel should be diverted to help with the search - and happily, their craft found him.

A source told People magazine: "Leo and his friends and their boat captain decided to join the search and their efforts resulted in helping save a man's life.

"The boat crew were happy to try and assist - even more so that they were able to help get the man to safety."

And it seemed the Once Upon a Time in Hollywood star's boat was the only one able to help the stranded crew member, who fallen overboard from a Club Med yacht near the island of Saint Martin.

Another source told Entertainment Tonight: "They were the only responders there looking for him, hours away, in the middle of the ocean.

"Everyone on board was looking for him in rough water [including Leonardo] The man was waving his hand and was found an hour before it got dark."

The 24-year-old French man had been treading water for nearly 11 hours before he was rescued and when he was found, was severely dehydrated so was given food and water before being handed over to coastguards for medical treatment.

A source told The Sun newspaper ""The 'man overboard' was minutes from drowning when he was found.

"He had been treading water and still managed to flail his hands as Leonardo came near.

"It was not long before daylight disappeared, and there was a giant rainstorm closing in. The man was doomed.

"He thought he was dreaming after being rescued by one of the world's most famous faces.

"The captain put the man's chances of survival at one in a billion - like winning the lottery twice."