WEST PALM BEACH, Fla. -- The U.S. Coast Guard said Wednesday the search for two teen boaters who went missing off the coast of Florida nearly a week ago is continuing.

Earlier, an official said that the Coast Guard was suspending the six-day search for 14-year-olds Perry Cohn and Austin Stephanos. But Chief Petty Officer Ryan Doss, spokesman for the Florida Coast Guard district, said that any reports of the search ending are inaccurate.

The vague rule of thumb is that humans can survive three days without water and three weeks without food, one expert said, but examples defying that abound -- especially if people have supplies, wear life jackets or can cling to something. By Wednesday, it still wasn't clear if 14-year-olds Perry Cohen and Austin Stephanos fell into any of those categories.

"People will constantly surprise you," said Laurence Gonzales, author of four books on survival. "You'll think, 'Surely this guy is dead.' And you'll go out and there he will be alive."

The saga began Friday, when the boys were spotted buying fuel about 1:30 p.m. A line of summer storms moved through the area later that afternoon and when the teens didn't return on time, the Coast Guard was alerted and launched its search. The 5.8-metre boat was found overturned Sunday more than 300 kilometres north of where the boys started their journey. The search has continued day and night, as their families try to maintain hope against the fading odds of the teens' survival.

On Wednesday, as the search area grew, crews also planned a "first-light" search near Tybee Island, Georgia, where callers reported seeing something floating in the water Tuesday evening, said Coast Guard Petty Officer Anthony Soto. Crews combed the area Tuesday night but didn't find anything connected to the search for the missing boys, officials said.

"As time goes on, certainly the probability of finding someone alive does decrease, but we're still within the timeframe where it's definitely possible to find somebody alive," Doss said, noting others have survived days or even a week at sea. "We know it can happen and we're hoping it happens again."