TEQUESTA, Fla. — Two teens remained lost in the Atlantic on Tuesday as their families and authorities tried to maintain hope against the fading odds of their survival.

The Coast Guard pressed ahead with a fifth day of searches for the boys while their families coordinated air searches of their own, insistent that Perry Cohen and Austin Stephanos were competent seamen and athletic young men who still could be found alive. But the relentless hunt by sea and air turned up no clue where the 14-year-olds might have drifted from their capsized boat, and the potential for finding them alive dimmed.

“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.”

The boys grew up on the water, constantly boated and fished, worked at a tackle shop together and immersed themselves in a life on the ocean. Perry’s family said he learned to swim before he took his first steps. And though some questioned why the boys were out boating alone, others defended their families and said such independent teen outings are commonplace among those with a passion for the water.

Clive Botha, a neighbor and friend of Perry’s family, said his own children took a boat out alone as teens and cruised local waterways, even as he forbade them from the deep ocean waters.

“We always told our kids to not go out of the inlet, but kids will be kids, you know?” he said. “I get goosebumps. In my heart, they could have been my kids.”

Perry’s stepfather, Nick Korniloff, said his stepson was supposed to remain on the Loxahatchee River and the Intracoastal Waterway during the outing with his friend, as they had numerous times before. Although they clearly ended up in the ocean waters, Korniloff said he didn’t believe the boys were heading to the Bahamas, as some have speculated.

“It’s a bit of a surprise to see, for us, that they went offshore,” Korniloff said.

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 at 5 p.m. and launched its search. 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.

The boys may be reaching the boundaries of human survival, but with many unknowns, anything remained possible.

The Coast Guard said crews would continue focusing on waters off northern Florida and southern Georgia overnight Tuesday into Wednesday. The families pledged a $100,000 reward in the search and numerous friends and strangers took to planes searching for clue.