REHOBOTH BEACH, Del.
When Ocean City tourist Greg Aulisio first heard the boys crying for help, out in the water beyond the breaking waves, he was not sure they were serious.
"I asked my wife, 'Are they kidding?' " he said, "and she goes, 'I don't think they are.' "
Aulisio, a strong swimmer, did not hesitate. He dropped his glasses into his wife's lap and plunged into the ocean, only to find that the two frightened young brothers were caught in one of the deadliest of water hazards: a rip current.
"I saw their boogie board going out to sea, and that's when I knew they were really in trouble," said Aulisio, 42, of Nanticoke, Pa.
Every summer, swimmers of all ages and skill levels get into trouble in the ocean and other large bodies of water. And more often than not, the force at work is the rip current.
This year, the perennial threat has suddenly drawn alarm as clusters of swimmers have drowned in Florida and Michigan. The deaths have prompted safety officials to renew often-unheeded warnings.
The strong, treacherous currents -- which can pull swimmers far from shore and tire them out if they attempt to fight it -- are the third-leading cause of weather-related deaths, after heat and flash floods, said Paul Houle, a marine meteorologist with the National Weather Service. Lightning deaths, which get more attention and inspire more fear, rank fourth.
About 90 percent of the 3,000 to 4,000 rescues by the Ocean City Beach Patrol each summer involve swimmers caught in a rip current, said Beach Patrol Capt. Butch Arbin. And in a single day, lifeguards in Rehoboth have made as many as 50 saves from the swift-moving currents, Rehoboth Beach Patrol Lt. Josh Tootell said.
But despite red flags and posted warnings, despite safety officials' repeated efforts to educate the public, about a hundred swimmers in the United States drown each year -- and untold others barely escape death -- because they are overcome by rip currents.