A jogger jumped in to rescue Margaritis, WPIX reported. He was able to free her from the paddleboard and bring her to shore, where first responders met them and attempted life-saving techniques.
She was then taken to a hospital, where she was pronounced dead.
Police said Margaritis was wearing a flotation device around her waist, the Times reported. The names of the other women she was paddleboarding with have not been released.
"She was a hero in my eyes," her mother, Jean Weber, told Newsday. "A very good kid. She wanted to save somebody else. She was always kind."