Deputies said Cottrell and his wife, Cheyenne Hedrick, also 22, were swept out to sea by a rip current.
The couple had been married for three days.
According to the police report, Cottrell "started to freak out" and Hedrick tried to help him after he began to struggle but "was unable to help due to him pulling her under."
A person who heard screams coming from the ocean grabbed his paddleboard and was able to grab Cottrell and bring him back to the beach, where lifeguards started to perform lifesaving measures.
Chloe Molinaro was on the beach Tuesday with her friends as rescuers tried to save Cottrell's life.
"So many people were hovering over," she said. "They knew it wasn't going to turn out well."
He was taken to Flagler Hospital where he was pronounced dead, the Sheriff's Office said.
Action News Jax reporter Ryan Nelson contacted Hedrick by phone but said she was too emotional to speak.
She allowed Action News Jax to share what she wrote on Facebook: "Never did I think at 22 would I be a wife and then a widow so quickly. Please pray for (me) and all families."