"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."
Scouring the ocean expanse is a long, tedious mission. 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.
On Tuesday morning, the eight-person crew of the C-130 Hercules Coast Guard plane based out of Clearwater, Florida - including a public affairs officer and an Associated Press reporter - left Florida's Gulf coast at midmorning and flew eastward.
Once the plane cleared the state's other coast and was over the Atlantic, it dropped to 500 feet above the murky ocean. The crew eased open the back cargo ramp and two men flopped on their bellies so they could search the sea below.
It wasn't an easy task. Around noon, the water was the same gray-blue as the sky; the horizon invisible, hazy. Spotting something in the water involves a little luck and a lot of training and experience.
"You search like it's your mom out there," Petty Officer Garrett Peck said.
The Coast Guard spent the day searching for the boys while their families coordinated air searches of their own, insistent that the teens were competent seamen and athletic young men who still could be found alive.
"Still trying to stay positive. Everyone still has to stay positive," the teens' friend,Alivia Smallegange, told CBS Miami.
But the relentless hunt by sea and air turned up no clue where the 14-year-olds might have drifted from their capsized boat.
For hours, the Coast Guard plane flew in a grid pattern. The pilot, 25-year-old Lt. Janelle Setta said, piped music over the plane's communications headsets, explaining that it keeps morale up, helps the crew stay awake and gives them something to chat about during the long hours of searching.
Two petty officers combed the water, and others scoured the ocean from windows. Another crew member used a joystick to manipulate a camera that scanned the ocean, somehow not becoming seasick from the water's motion.
Occasionally, they'd spot something and loop around, sometimes dropping flares. A white rectangular shape that looked like a pillow. A box. Something greenish that gave them hope but turned out to be a fishing net.
"I'm pretty sure this is going to turn out to be algae," one of the crew said over the communications system.
"Better safe than sorry," replied another.
After nearly 10 hours of flying, without success, the crew looked bleary and tired as it diverted the plane around a lightning storm on its way home.
The saga began Friday. A line of summer storms moved through the area that afternoon, and when the teens didn't return on time, the Coast Guard was alerted. The 19-foot boat was found overturned Sunday off Ponce Inlet, more than 180 miles 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.
"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," said Coast Guard Chief Petty Officer Ryan Doss, noting others have survived days or even a week at sea. "We know it can happen and we're hoping it happens again."
Dr. Claude Piantadosi, a Duke University medical professor who authored "The Biology of Human Survival: Life and Death in Extreme Environments," said the obstacles were steep but agreed the teens could still be alive. The variables, he said, are countless: Could they have clung to a cooler, perhaps, or used it to capture rainwater? Could they have avoided the threat of sharks or other marine life? Could they fight their own thirst and thoughts of drinking the saltwater?
"Even though the odds are against them, I certainly wouldn't call off the search," he said. But, he added: "Every hour that passes at this point, the chances go down."