Andrew Eddy, 30, was on a private boat with his wife Margot Dukes-Eddy and their family on Sunday morning, when he decided to go for a swim.
They were at Sombrero Reef, according to the Monroe County Sheriff's Office, and just as Mr Eddy slid into the ocean, a large shark took a bite of his shoulder. The shark was described by witnesses as a bull shark.
Deputy Christopher Aguanno wrote in his report: "Dukes saw the shark's dorsal fin and then blood filling the water.
"Dukes, without hesitation, dove into the water and pulled Eddy to the safety of the boat."
A desperate 911 call was released, which you can hear in the footage above.
In the clip, a woman can be heard frantically screaming: "Can someone help me?"
She then adds: "We're at the Sombrero lighthouse and my son-in-law just got bit by a shark in the shoulder. We need help immediately."
A man than takes over the call and, speaking much calmer, he says: "Hello, this is an emergency. We're in the middle of the ocean. Someone has got to get to Sombrero Key lighthouse. Please send emergency help."
The call taker asks: "Is there any way you can bring him in?"
To which the man responds: "No, there's no way we can bring him in. It's a four-mile drive. He's awake and yes, he's breathing. The bleeding is somewhat controlled.
"It's basically a big chunk taken out of his shoulder."
Eddy was driven by boat to Sombrero Beach which is located in Marathon. Medics with the city's Fire Rescue were waiting for him to arrive.
According to the Miami Herald, Monroe County's helicopter air ambulance flew him to Ryder Trauma Center at Miami's Jackson Memorial Hospital.
The publication did not get an immediate response to a request for comment but a Jackson Memorial Hospital spokeswoman said this week that the family has requested privacy.
According to the latest information from the University of Florida's International Shark Attack File, Monroe County has had 17 unprovoked shark bites since 1882.
Despite that relatively low number, George Burgess, who retired as director of the University of Florida's International Shark Attack File, agreed that it was likely a bull shark that bit Eddy.
Chosen for YouChosen for You
Most Read StoriesMost Read