The U.S. Coast Guard and an off-duty lifeguard in a borrowed boat combined to rescue a teenage kayaker early Thursday morning after he went missing about 10 hours earlier off Oahu South Shore.

The Honolulu Fire Department received a 911 call at 6:28 p.m. Wednesday reporting a missing kayaker.

The 17-year-old boy, Kahiau Kawai, had been kayak­ing with a group traveling from the Ala Wai Channel to Diamond Head and back when he was noticed missing on the return trip.

After receiving the call, HFD responded with 16 units and about 48 personnel, initiating a shoreline search. The Hawaii Airports Division and the U.S. Coast Guard also joined the effort. The search area ranged from the east end of Diamond Head to Nanakuli, and about 4 miles offshore.

Noland Keaulana, an off-duty Honolulu Ocean Safety lifeguard and a member of the Polynesian Voyaging Society, borrowed a boat from PVS and began searching at 8:30 p.m.

Keaulana, a lifeguard for about 16 years, said at a news conference Thursday that he learned Kawai had gone missing, knew the family and felt he had to help.

“I know last night I wouldn’t be able to sleep if I didn’t go out there,” said Keaulana, who said he is a father himself.

At about 4:20 a.m. a U.S. Coast Guard C-130 aircraft spotted the kayaker offshore near the Waikiki Natatorium and marked his location with a flare.

Keaulana reached Kawai and shared how relieved he was to see the boy still had his head above water and that he was treading in the ocean while clinging to the kayak.

He pulled Kawai into the boat and warmed him up with towels and blankets, then took him back to the Ala Wai Boat Harbor, where Emergency Medical Services and HFD were waiting.

EMS took over care at 5:28 a.m. and treated the teen for hypothermia, extreme dehydration and exhaustion. Kawai was awake, alert and talking, according to EMS spokesperson Shayne Enright.

“We’re just thrilled to be able to share this good outcome with you,” said Enright. “This is the perfect example of interagency, joint response, where everybody came out, everyone, to do whatever they could to save this boy’s life.”

Paramedics took Kawai in serious condition to a hospital emergency room where he was able to rejoin his family.

The family, including parents Ka‘ala and Kelehua Kawai, issued a statement thanking the entire search team.

“The Kawai ohana would like to thank the state, City & County, and federal agency rescue teams, who worked tirelessly through the night to search for our son, Kahiau,” said the Kawais in the statement. “A very special mahalo to good Samaritans, friends and family, and especially lifeguard and waterman Noland Keaulana who went out on his own to search for Kahiau all night, never giving up, using his instincts and knowledge of the ocean.

“Kahiau, who could see rescue teams looking for him, was strong, resilient and brave for 11.5 hours in the dark, and is grateful to be back with his family and friends,” the Kahiaus said. “Mahalo to the doctors and nurses caring for him. And lastly, thank you to everyone who prayed and believed God for and with us for his safe return.”