A 22-year-old man has been rescued by his family after being dragged by the current away from the shore and got lost at sea in shark-infested waters.

Dylan Gartenmayer described the dramatic hours he spent alone in the sea as he watched the sunset nearing and the darkness spreading around him.

He had gone drift diving with friends near Key West, off Florida's coast on January 19, when a strong current swept him away from the boat and separated him from the group.

He said: "The current ended up taking me faster and faster from them, and it got to the point where the boat just disappeared.

"At that point, I realised things were starting to get serious."

Dylan was feeling cold and started to shiver.

He was terrified to see reef sharks swimming as close as 10 feet from him.

Eventually, he found a piece of bamboo to cling onto and after swimming for a while more, he found two white mooring balls and tied them to himself to stay afloat.

He said later in an interview with Today: "Watching that sun drop was kind of like making my heart sink.

"I was like, 'Oh, this is going to be a long night out here.' That was my idea with the buoys, was tying those together and trying to get up as high as I can, keep a little warmth and put less of my body in the water for any potential predators."

Meanwhile, his friends and family gathered together and boarded his granddad's boat in a bid to locate and rescue him.

His cousin Priscilla Gartenmayer, told CNN: "The first thought was that he blacked out while diving and drowned. It was horrible – the worst feeling I’ve ever felt."

Dylan's family shared the dramatic moments of the search for him on Facebook.

The family sped in agony towards the coordinates where Dylan was last seen, hoping to locate him before the sunlight ceased entirely.

Priscilla said: "Everything was silent on the boat until the flashlight hit him and he put his hands up – we finally knew he was OK."

Dylan's mum, Tabitha Gartenmayer said: "It definitely had to be a miracle. It had to be God protecting him the whole time, our angels above, because for us to land right on him, you could see it’s a needle in a haystack out there.

"He was so smart to get the buoys, to know that his head wasn’t going to be enough to find him."

Dylan recalled: "Seeing them stop and just point right at me, I was like, ‘Oh, my God. They see me'."

His friends and family can be seen in a video hugging and squeezing him, crying "Oh my God" and saying his name over and over. Dylan’s first request was for water, his cousin said.

The Coast Guard arrived and checked on him. His core temperature was slightly low. They took him to the station for observation for about an hour until it was back to normal, his family said.

His mum couldn't hold back her tears when she described the heartwarming moment she saw her son: "It literally took my breath away. I couldn’t even breathe, everything just went away. This is definitely a miracle."

Coast Guard spokesperson Eric Rodriguez said Gartenmayer was reported missing at 4.19pm local time (9.19pm GMT) and was rescued seven miles southeast of Key West two hours later.