Long Lost Son (2006) on Netflix

Plot summary

Kristen Sheppard is a law student preparing to divorce her husband Quinn Halloran, who had hoped they would start a new life on the Florida Keys. On one of his monthly weekends with their four-year-old son Mark, Quinn takes the sail yacht Ocean Dreamer out; the boat loses its mast and both are declared lost at sea. Fourteen years later Kristen, now an attorney and married to Steve Collins, is watching a friend's Caribbean holiday video when she recognizes a man calling himself John Williams, and his son Matthew, who run a dive charter named Phoenix on the island of Santa Alicia. She takes the man to be Quinn and presumes the boy is their son Mark.