A man was swept out to sea while swimming off Long Island Monday morning — but he treaded water for five hours and created a makeshift flag to attract his rescuers.

Dan Ho, 63, was in the water at Cedar Beach in Babylon around 5 a.m. when strong currents carried him two-and-a-half miles off the coast, according to the police.

The Copiague man miraculously kept himself afloat without any flotation devices and found a broken fishing rod floating in the water.

Ho then tied his shirt to the rod to create a flag to try to wave down help, cops said.

By 10:30 a.m. his ingenuity proved fruitful. He was spotted by two men on a motorboat — retired FDNY marine engineer Jim Hohorst and pal Michael Ross — who pulled Ho out of the ocean and onto their vessel, a 2007 Albin, Suffolk PD said.

Hohorst then alerted emergency responders through VHF radio and the Suffolk County Police Department’s marine unit rushed to meet the civilian boat.

Officers Bernadette Benjamin and Robert Jenkins transferred Ho onto their ship, the Marine Juliet, where they immediately treated him for hypothermia.

Ho was conscious and alert but unable to stand up due to exhaustion, police said.

He was brought ashore to the US Coast Guard Station on Fire Island where he was treated by Coast Guard medics before he was taken to Good Samaritan University Hospital in West Islip via ambulance.