The man began swimming for his life when the boat he was on overturned in treacherous waters at the Jupiter Inlet, Florida.
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After the boat capsized, the man did everything he could to keep his head above water, ABC News reports.
When the teenager spotted him, he paddled out to safe him- giving up his board and swimming alongside the man.
Brave Sam Ruskin, 13, saved a man's life
The boat capsized in the rough waters
Dramatic video footage shows how violent the current was, with rapid and fierce waves.
Young Sam Ruskin heard the man's cries for help, and his dad said he "didn't even blink an eye" before going to help him.
Telling the story, Sam said at first he saw boxes around the boat and wondered what was going on.
The dramatic incident was captured by drone footage
Sam spotted boxes around the capsized boat
"There was this guy coming around the Inlet, so I paddled to the end of the Inlet where the current is and I gave him my surf board," he said.
"I was swimming next to him so I was really struggling just to get out of that area."
Sam's dad Ryan said he was not surprised by his son's actions, explaining that the rescue fit in with his character.
Sam gave the man his surf board and swam next to him
"He didn't even blink an eye, he just went over there, jumped off his board, handed it to a grown man, saved his life, came back and said 'hey what's for dinner dad'."
Ryan said Sam was very calm about the whole thing but the footage has since gone viral.