William Durden, 61, told CNN affiliate Bay News 9
that he was fishing by himself on his boat, when he fell overboard Wednesday on the Homosassa River north of Clearwater, Florida. He was not wearing a life jacket.
Durden's wife called authorities when he didn't return home.
He was found the next day -- about 15 nautical miles southeast of Aripeka, Florida -- and rescued by the Coast Guard.
Durden, who said he was a former Navy pilot, had been treading water for 20 hours. How did he get through the ordeal?
"I went through different phases, first couple hours, 'I'll find some way to wave down and get on somebody's boat,' then sundown comes and...'I'm gonna have to plan for nighttime now.' "
Durden said making it through the night was "the hairiest part of the ordeal." He got cold and started to shake, feeling "hypothermic."
When the sun came up he kept thinking "I'm gonna get picked up today."
His optimism paid off. After two hours he was spotted by a Coast Guard helicopter.
"I looked a little bit closer and it had two arms and it was waving at me, my adrenaline spiked," USCG Petty Officer Jacob Latour told the affiliate.
A Coast Guard rescue swimmer jumped in, and was surprised to find Durden in good condition.
"It's very rare that we find somebody, a single person in the water especially after 20 hours with no life jacket and it is very exciting that we found somebody," said Latour.
His 22-foot boat was found by Florida Fish and Wildlife officials in St. Martin's Key.
And what about encounters with sea creatures? Durden said he felt fish hitting his legs. But "was just praying that no big shark would come out and decide to have me for dinner."