The man, Lo Siu-cheung, spent Saturday night at the beach with about a dozen friends and schoolmates to celebrate the festival and enjoy a barbecue. Early yesterday, after most had gone home, Lo tagged along when two remaining members of the group decided to have a dip around 7am.

A source said Lo did not know how to swim, and was paddling around clinging to a float. About 10 meters out, he got sucked under a wave and failed to surface.

Marine police boats and helicopters were dispatched after one of Lo's friends sounded the alarm. They scoured the area for several hours.

Firemen searched the shore as rough seas made it difficult for divers who were attached to safety cables. Meanwhile, police conducted their own investigations, interviewing Lo's friends.

One friend, surnamed Tse, said he called the police at 7.31am when Lo failed to surface.

About an hour later he was seen sitting on a bench with tears streaming down his face. "I couldn't save [him], it's already been an hour," he mumbled when police asked him for more details.

Ironically, red flags were hoisted at the beach at 9.56am - two hours after the disappearance - owing to the high waves.

In Sai Kung, a man who fell into the sea while fishing was rescued by three fishermen after drifting for about an hour.

Kong Ka-lok, 47, was alone on the rocky shores off Tung Lung Chau when he was swept away by a freak wave.

Kong struggled to get back to shore but failed and drifted for about an hour before he saw the fishermen and shouted for help.

He was plucked from the sea and taken to Eastern Hospital, where his condition was reported as stable.

A 22-year-old was also taken to Eastern Hospital after being injured in the surf off Sai Kung's Tai Wan Beach at about 4pm yesterday.

Apart from yesterday's incidents, there have been seven drownings in Sai Kung this summer.

The last victim was Polytechnic University student Cheung Tsz- him, 21, who drowned off Tai Long Sai Wan on September 27.